Some anti-Muslim websites say Islam allows adult men to be breastfed by women and they quote some hadith to this effect. Is it true?
In the name of Allah, the Beneficent, the Merciful
There was a specific case in which the Prophet allowed a servant to drink the breast milk of a woman that had been poured into a cup for the purpose of putting at ease the master of the household. The narration is as follows:
Aisha reported: Salim, the freed slave of Abu Hudhaifa, lived with him and his family in their house. The daughter of Suhail came and said: Salim has attained puberty as men do, he knows what they know, and he enters our house freely, and I sense that this bothers the heart of Abu Hudhaifa. So the Messenger of Allah, peace and blessings be upon him, said:
أَرْضِعِيهِ تَحْرُمِي عَلَيْهِ وَيَذْهَبْ الَّذِي فِي نَفْسِ أَبِي حُذَيْفَةَ
Let him be fed with breast milk and he will become unlawful for you in marriage, then the feelings in his heart will disappear.
Source: Sahih Muslim 1453, Grade: Sahih
She returned and said, “I fed him with breast milk and the feelings in Abu Hudhaifa’s heart disappeared.”
It is interpreted that the milk he drank was from a cup and not from her breast. The purpose of him drinking the milk was to ease the heart of Abu Hudhaifa, so that Salim would be closer to his family and he would not worry about his wife being alone with an unrelated man. If Salim had drank from her breast, this would have defeated the purpose to begin with, which was to practice modesty.
Therefore, Ibn Hajar comments:
فَإِنَّ عِيَاضًا أَجَابَ عَنِ الْإِشْكَالِ بِاحْتِمَالِ أَنَّهَا حَلَبَتْهُ ثُمَّ شَرِبَهُ مِنْ غَيْرِ أَنْ يَمَسَّ ثَدْيَهَا قَالَ النَّوَوِيُّ وَهُوَ احْتِمَالٌ حَسَنٌ
Al-Qadi Iyad responds to this problem with the interpretation that the milk was put into a cup and he did not drink it from her breast. An-Nawawi says: This is a good interpretation.
Source: Fath ul-Bari
Furthermore, this was a special concession for Salim and Abu Hudhaifa in this specific case and the companions of the Prophet understood that this is not a general rule.
Umm Salama, the wife of the Prophet, would say that all of the Prophet’s wives disclaimed the idea that one with this type of fosterage should enter upon them freely. Aisha said:
وَاللَّهِ مَا نَرَى هَذَا إِلَّا رُخْصَةً أَرْخَصَهَا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لِسَالِمٍ خَاصَّةً فَمَا هُوَ بِدَاخِلٍ عَلَيْنَا أَحَدٌ بِهَذِهِ الرَّضَاعَةِ وَلَا رَائِينَا
By Allah, this was only a concession given by the Messenger of Allah for Salim alone, and we do not allow those with this type of fosterage to enter our homes and we do not subscribe to that view.
Source: Sahih Muslim 1454, Grade: Sahih
Therefore, it seems as if the publishers of the websites you mentioned have misunderstood the narration, its interpretation, and its ruling. We ask Allah to guide them to the truth.
Success comes from Allah, and Allah knows best.