Good Manners and Form (Al-Adab)

Bukhari :: Book 8 :: Volume 73 :: Hadith 26

Narrated Abu Huraira:

Allah's Apostle kissed Al-Hasan bin Ali while Al-Aqra' bin Habis At-Tamim was sitting beside him. Al-Aqra said, "I have ten children and I have never kissed anyone of them," Allah's Apostle cast a look at him and said, "Whoever is not merciful to others will not be treated mercifully."