(18) باب رَحْمَةِ الْوَلَدِ وَتَقْبِيلِهِ وَمُعَانَقَتِهِ
Narrated Abu Huraira:
Allah's Messenger (ﷺ) kissed Al-Hasan bin `Ali while Al-Aqra' bin H`Abis at-Tamim was sitting beside him. Al-Aqra said, "I have ten children and I have never kissed anyone of them," Allah's Messenger (ﷺ) cast a look at him and said, "Whoever is not merciful to others will not be treated mercifully."
Reference: Sahih al-Bukhari 5997
In-book reference: Book 78, Hadith 28
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 73, Hadith 26