Alqamah bin Qays (may Allah have mercy on him) narrates: I came to Syria and met Sayyiduna Khalid bin al-Walid (may Allah be pleased with him), and I heard him narrating: "Between me and Ammar bin Yasir (may Allah be pleased with him) there occurred some of what occurs between people. I turned to Ammar and rebuked him harshly, so he went to the Prophet (peace and blessings be upon him) and complained about me. When I saw him complaining about me, I too turned on him (with harsh words). He (Ammar) said: 'O Messenger of Allah, do you not see what he is saying while you are present?' He (peace and blessings be upon him) said: 'Steady, O Khalid! Say nothing but good, for whoever hates Ammar, Allah will hate him, and whoever shows enmity to him, Allah will show enmity to him.' When I heard that, I began seeking to meet Ammar until I met him, and I apologised to him, and whatever he had held in his heart against me went away."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3820