Musnad Ahmad 770:43

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, he said: I heard Abu Ishaq say: Jarir ibn ‘Abdullah was in an expedition in Armenia. He said: A famine or hunger afflicted them. He said: So Jarir wrote to Mu‘awiyah: "I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Whoever does not show mercy to the people, Allah the Mighty and Majestic will not show mercy to him.'" He said: So he sent for him, and he came to him and said: "Did you hear it from the Messenger of Allah, peace and blessings of Allah be upon him?" He said: "Yes." He said: "Then send them back and provide for them." Abu Ishaq said: "My father was in that army, and he brought a velvet cloth from what Mu‘awiyah had provided him with."