Abu Hurairah (May Allah be pleased with him) reported

The Prophet (ﷺ) kissed his grandson Hasan bin 'Ali in the presence of Aqra' bin Habis. Thereupon Aqra' remarked: "I have ten children and I have never kissed any one of them." The Messenger of Allah (ﷺ) cast a glance upon him and said, "He who does not show mercy to others, will not be shown mercy."

[Al-Bukhari and Muslim].