It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that once Aqra' bin Habis saw that the Noble Prophet (peace and blessings be upon him) was kissing Hazrat Hasan (may Allah be pleased with him). He said, "I have ten sons, but I have never kissed any of them." The Noble Prophet (peace and blessings be upon him) said, "He who does not show mercy to others, mercy will not be shown to him."