Musnad Ahmad 432:3

Yazid ibn Harun narrated to us, Al-Awwam ibn Hawshab informed us, from Salamah ibn Kuhayl, from Alqamah, from Khalid ibn al-Walid, who said: There was a dispute between me and Ammar ibn Yasir, and I spoke harshly to him. Ammar went to complain about me to the Prophet, peace and blessings of Allah be upon him. Khalid came while he was complaining about him to the Prophet, peace and blessings of Allah be upon him. He said: He began to speak harshly to him, and he did not increase him in anything but harshness, while the Prophet, peace and blessings of Allah be upon him, was silent and did not speak. Ammar wept and said: "O Messenger of Allah, do you not see him?" The Messenger of Allah, peace and blessings of Allah be upon him, raised his head and said: "Whoever shows enmity to Ammar, Allah will show enmity to him, and whoever hates Ammar, Allah will hate him." Khalid said: "So I went out, and there was nothing more beloved to me than the pleasure of Ammar. I met him, and he was pleased." Abdullah said: "I heard it from my father twice."