All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We have not come across this Hadeeth in either Al-Bidaayah wan-Nihaayah or in any other resource books of Hadeeth.
It might be that you are referring to what Ibn Hajar mentioned in At-Talkhees Al-Habeer, as he said: "The Hadeeth that a delegation came to the Prophet and with them was an attractive boy, so he [the Prophet] made him sit behind him and said: “I fear what happened to my brother Daawood”; Ibn As-Salah said: “This is a Dha’eef (weak) and baseless Hadeeth.” Ibn Shaaheen reported it in Al-Afraad from Mujaalid from Ash-Sha’bi who said: “A delegation from ‘Abd Al-Qays came to the Prophet and with them was an attractive, beardless boy, so he [the Prophet] made him sit behind his back and said: “The mistake of Daawood was looking (i.e. at what is forbidden).” Ibn Al-Qattaan mentioned it in the book, Ahkaam An-Nathar, and he graded it as Dha’eef. Also, Ahmad ibn Is-haaq ibn Ibraaheem ibn Nubayt ibn Shareet reported it in his Nuskhah, and from his route Abu Moosa also narrated it in At-Tarheeb and its chain of narrators is very weak. Shaykh Al-Albaani said in his book, Irwaa’ Al-Ghaleel, about this Hadeeth: “It is fabricated.”
As regards the ruling of looking at beardless men, then there are some details about it which were mentioned by Shaykh Al-Islam Ibn Taymiyyah as he said: “Looking at beardless men is of three types:
1- Looking at them with lust; this is forbidden according to the agreement of all the scholars.
2- Looking at them with absolutely no lust, like a pious man looking at an attractive son or daughter of his, or at his mother. This is not accompanied by lust unless the man is extremely sinful; so when it is accompanied with lust, it is forbidden.
3- Looking at them with no desire while fearing to incite one’s desires; there are two opinions according to the Hanbali School of jurisprudence; the most correct of which, which Ash-Shaafi’i is also cited as saying, is that it is not permissible…and this is the strongest opinion.” [End of quote]
Allaah Knows best.