That his father took him to Allah's Apostle (Sallallahu 'Alaihi Wa Sallam) and said, "

Narrated An-Nu'man bin Bashir (Radi-Allahu 'anhu):

That his father took him to Allah's Apostle (Sallallahu 'Alaihi Wa Sallam)
and said, "I have given this son of mine a slave." The Prophet (Sallallahu
'Alaihi Wa Sallam) asked, "Have you given all your sons the like?" He
replied in the negative. The Prophet (Sallallahu 'Alaihi Wa Sallam) said,
"Take back your gift then."

Bukhari Vol. 3 : No. 759