The Arabic expressions like waladul baghaya or ibnal haram all describe people who are evil rather than of illegitimate descent.It is an Arabic expression which is used by many and here is an example from a scholar of the Sunni Ulama:
Imam Novi commented, “One should not be the first to embark upon severity or ridicule of the pagans, so that Muslims should safeguard their tongues against undesirable language. But when the other side embarks upon abuse and there should be need of defense against their mischief, it is permissible, as the Holy Prophet, peace and blessings of Allah be upon him, directed.”
Some anti Ahmadi opponents also accused Ahmad(as) for calling some of his opponents waladul haram. This is also because of their ignorance and becomes clear when we look at what the Qur’an states and how it speaks in a similar manner.
This is proven clearly by the incident with Noah(as) and his son:
And Noah cried unto his Lord and said: ‘My Lord, verily, my son is of my family, and surely, Thy promise is true, and Thou art the Most Just of judges.’He said: ‘O Noah, he is surely not of thy family; he is indeed a man of unrighteous conduct. So ask not of Me that of which thou hast no knowledge. I advise thee lest thou become one of the ignorant.(Chapter 11 Verse 46-47)
Ahmad(As) states:
“Some people calling themselves Muslims, who should be called semi-Christians, were so pleased that Abdullah Atham had not died within fifteen months that they could not restrain their joy. They made announcements in which, according to their habit, they expressed themselves in intemperate language and on account of their personal rancor against me they even attacked Islam inasmuch as my controversy with the Christians was in support of Islam and did not involve the question of my being the Promised Messiah. They might have considered me a disbeliever, or Satan, or Anti-Christ, but the discussion related to the truth of the Holy Prophet, peace and blessings of Allah be upon him, and the superiority of the Holy Quran. A truthful one is he who believes sincerely in the Khatamul Anbiya, peace and blessings of Allah be upon him, and accepts the Holy Quran as the Word of God. He who considers that Jesus was God and rejects the prophet hood of the Khatamul Anbiya, peace and blessings of Allah be upon him, is a liar. I had cited a revelation of mine in support of this, but I have to affirm in sorrow that in order to prove me false the opposing divines did not keep in mind the honor of Allah and His Messenger and did not in the least mind the conclusion which the enemy would draw from defeat of the Islamic side. Mian Sanaullah, Saadullah, Abdul Haq, and others, having conceded the victory of the Christians, why do they complain about the Christians that they use their alleged victory as an argument against Islam, when the whole controversy was about the truth or falsehood of Islam and Christianity and not about any particular doctrine of mine.” (Anwarul Islam p. 48)
He states further:
“For proving himself legitimately born it was necessary for such a one if he considered me false and the Christians as victorious to meet effectively the argument that I have set forth … It is a sign of the bastard that he does not adopt the straight path and continues to love the ways of wrong and injustice.”(Anwarul Islam pg 30)
Similar statements of scholars:
Imam Abu Hanifa(ra) said: “A person who charges Ayesha, may Allah be pleased with her, with adultery is himself the issue of adultery.”
Imam Fakharuddin Razi stated: An evil sperm drop produces an evil child ( (Tafsir Kabir, Vol. VIII, p. 188)
The Qur’an has also used harsh language when needed.
And surely, you have known the end of those amongst you, who transgressed in the matter of the Sabbath. So We said to them: ‘Be ye apes, despised.(Chapter 2 Verse 66) (Many scholars have agreed that this ayah refers to the condition of the people)
Again Allah states:
The likeness of those who were made to bear the law of Torah, but would not bear it, is as the likeness of an ass carrying a load of books. Evil is the likeness of the people who reject the Signs of Allah. And Allah guides not the wrongdoing people.(Chapter 62 Verse 5)
Allah further states:
And yield not to any mean swearer, Backbiter, one who goes about slandering, Forbidder of good, transgressor, sinful, Ill-mannered and, in addition to that, of doubtful birth.This is because he possesses riches and children.(Chapter 68 Verses 11-15)
Allah states again:
Say, ‘Shall I inform you of those whose reward with Allah is worse than that?They are those whom Allah has cursed and on whom His wrath has fallen and of whom He has made apes and swine and who worship the Evil One. These indeed are in a worse plight, and farther astray from the right path(Chapter 5 Verse 61)
Muhammad(Saw) states some harsh words in regards to the latter day ulema also. Here are two Ahadith with similar language by Muhammad(saw) which shows the condition of the latter day ulema :
عن علي بن أبي طالب رضي الله عنه، قال : قال رسول الله صلى الله عليه وسلم:”يوشك أن أو سيأتي على الناس زمان لا يبقى من الإسلام إلا اسمه، ولا يبقى من القرآن إلا رسمه، مساجدهم يومئذ عامرة وهي خراب من الهدى، علماؤهم شر من تحت أديم السماء، منهم أو من عندهم خرجت أو تخرج أو يمدح الفتنة وفيهم تعود“
‘Alī ibn Abī Ṭālib (ra) narrates that the Messenger of Allāh (sa) said: “A time will come in the near future when there will be nothing left of the Islam except its name. And there will be nothing left of the Holy Qur’ān except its words. The mosques of that age will apparently be full of people, but will be empty of righteousness. Their ‘Ulamā’ will be the worst creatures under the heaven. Discourse will rise from them and will come right back to them.”(Mishkat)
And:
“There will arise a great turbulence among my people and in their terror they will have recourse to their divines and suddenly they will find them in the guise of apes and swine.”(Kanzul Ummal, Vol. VII, p. 90)
Ahmad(as) in Izala Auham has stated:
“Abuse is one thing and a correct description, however bitter and harsh, is quite another, It is the duty of every speaker of truth to convey the truth to an erring opponent even though he might thereby.”
He also states:
My words had assumed some severity against my opponents in my writings, but I was not the one to start such severity. Those writings were undertaken in reply to the severe attacks of my opponents. They had used such harsh and abusive language as called for some severity. This can be perceived by the comparison which I have instituted between the harsh language used by my opponents – and that used by me in the foreword of my book which I have called Kitabul Bariyyah. As I have just stated the harsh language used by me was by way of retort. It was my opponents who first used such language against me, I could have endured their harsh language without making a retort to it but I had recourse to a retort on account of two reasons: One, so that my opponents, being faced with severity in reply to their harsh strictures, might change their tactics and might revert in future to the use of civil language; and two, that the general Muslim public should not be aroused by the defamatory and provocative language used by my opponents.”( Kitabul Bariyyah, pp. 10-11)
Again Ahmad(as) states:
“We seek refuge with God against defaming righteous divines and civilized respectable people, whether they are Muslims or Christians or Aryas. We consider all of them worthy of honor. We are not concerned even with foolish people. Our severe language is employed only against those who have become notorious on account of their vile language and foul-mouthed utterances. We always mention in good terms those who are good and are not given to abuse and we honor them and love them like brothers.( Lujjatun Nur, p. 61)
And further:
“All ulema are not the same: Some of them are God-fearing while others are wrongdoers. Those who fear Allah, we always think well of them; Allah will soon guide them and they shall perceive the truth. When they are told to declare this man a kafir who is claiming to be the Messiah, they say ‘We will not say anything without full knowledge, and we fear Allah((Al-Huda, Ruhani Khazain Vol. 18, p. 320)