From Sahih Muslim (Hadith 6027):
A'isha (Allah be pleased with her) reported that there came a few desert Arabs to Allah's Messenger (ﷺ) and said:Do you kiss your children? He said: Yes. Thereupon they said: By Allah but we do not kiss our children. Thereupon Allah's Messenger (ﷺ) said: Then what can I do if Allah has deprived you of mercy? Ibn Numair said: (We has deprived) your heart of mercy
Reference: Muslim 6027