The Messenger of Allah ﷺ kissed Hasan bin Ali while Aqra bin Habis al-Tamimi was sitting with him.Aqra remarked, "I have ten children, and I have never kissed any of them."The Messenger of Allah ﷺ looked at him and said, "Whoever shows no mercy will be shown no 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 Al-Adab (5997), and Muslim in Al-Fadail (2318), both from the hadith of Zuhri, who said, "Abu Salama bin Abdul-Rahman narrated to us, from Abu Hurairah," and he mentioned it.