The Messenger of Allah ﷺ kissed Hasan bin Ali . Aqra bin Habis said, "I have ten children, and I have never kissed any of them."The Messenger of Allah ﷺ replied, "Whoever shows no mercy will be shown no mercy."
حدثنا روح بن عبادة حدثنا محمد بن أبي حفصة عن ابن شهاب عن أبي سلمة
أن رسول الله ﷺ كان يقبل الحسن بن علي رضي الله عنهما فقال الأقرع بن حابس إن لي عشرة من الولد ما قبلت منهم أحدا فقال رسول الله ﷺ من لا يرحم لا يرحم
Its isnad is sahih. Bukhari related it, 8/9, in the Book of Manners, chapter on mercy toward children, and Muslim in the Book of Virtues, 4/1809, no. 2318, chapter on his mercy ﷺ, and Abu Dawud in the Book of Manners, chapter on a man kissing his child, 4/355, no. 5218, and Tirmidhi in the Book of Righteousness, chapter on what has been said about mercy toward children, 4/318, no. 1911, where he said, hasan sahih, and Ibn Hibban, 553, no. 2239.