From Sahih Muslim (Hadith 2069):
Abu Huraira reported:While the Abyssinians were busy playing with their arms in the presence of the Messenger of Allah (ﷺ) 'Umar b. Khattab came there. He bent down to take up pebbles to throw at them (in order to make them go off). The Messenger of Allah (ﷺ) said to him: 'Umar, leave them alone
Reference: Muslim 2069