recited those books knew the beloved Prophet صَلَّى اللهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم better than their own sons.

It is stated in verse 146 of Surah al-Baqarah:

اَلَّذِیْنَ اٰتَیْنٰہُمُ الْکِتٰبَ یَعْرِفُوْنَہٗ کَمَا یَعْرِفُوْنَ اَبْنَآءَھُمْ ؕ

Those to whom We have granted the Book recognize that Prophet as they recognize their sons.^[1]

Mufti Aḥmad Yār Khān NaꜤīmī رَحْمَةُ الـلّٰـهِ عَـلَيْه writes under this verse:

The People of the Book (who had knowledge of the Torah and Injīl) recognised the beloved Prophet صَلَّى اللهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم. How well did they know him? How did they know him? Just as they know their own sons, such that if one’s child was to stand among a thousand children, a person would know which one is his son. A person does not even doubt for a second whether it is their child. Even hearing his voice and seeing his manner of movement from a distance, he knows that this is his son’s voice and the way he walks. Similarly, the People of the Book recognised the beloved Prophet صَلَّى اللهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم from his blessed appearance, his mannerisms, his speech, and every other quality of his.^[2]

The testimony of Sayyidunā ꜤAbdullāh b. Salām رَضِىَ اللّٰهُ عَـنْهُ

It is related:

When Sayyidunā ꜤAbdullāh b. Salām رَضِىَ اللّٰهُ عَـنْهُ, who was a major scholar of the People of the Book, accepted Islam, Sayyidunā ꜤUmar b. al-Khaṭṭāb رَضِىَ اللّٰهُ عَـنْهُ asked him, “What is the meaning of the verse which mentions that the people of the Book recognise the beloved Prophet صَلَّى اللهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم?”