The Messenger of Allah ﷺ kissed Hasan bin Ali while Aqra bin Habis at-Tamimi was sitting with him.Aqra said, "I have ten children, and I have never kissed any of them."The Messenger of Allah ﷺ looked at him and said, "Whoever does not show mercy will not be shown mercy."
قبل رسول الله ﷺ الحسن بن علي، وعنده الأقرع بن حابس التميمي جالسا، فقال الأقرع: إن لي عشرة من الولد ما قبلت منهم أحدا، فنظر إليه رسول الله ﷺ ثم قال: من لا يرحم لا يرحم.
Bukhari narrated it in Adab (5997), and Muslim in Fadail (2318), both of them through Zuhri, who said, Abu Salama bin Abdul-Rahman narrated to us, from Abu Hurairah, and he mentioned it. The wording is Bukhari's.