Musnad Ahmad 26:610

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, he said: I heard Abu Ishaq narrating from Abu al-Ahwas, from Abdullah ibn Mas'ud, that he said: Indeed, Muhammad, may Allah bless him and grant him peace, was taught the openings of goodness, its comprehensive expressions, and its conclusions. He said: "When you sit after every two rak'ahs, say: 'The greetings are for Allah, and the prayers and the good things. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us and upon the righteous servants of Allah. I bear witness that there is no god but Allah, and I bear witness that Muhammad is His servant and His messenger.' Then let one of you choose from the supplications what is most pleasing to him, and let him supplicate his Lord, the Mighty and Majestic, with it." And indeed, Muhammad, may Allah bless him and grant him peace, said: "Shall I inform you what *al-'addah* (slanderous gossip) is?" He said: "It is the tale-bearing that spreads between people." And indeed, Muhammad, may Allah bless him and grant him peace, said: "A man continues to speak the truth until he is recorded as a truthful one (*siddiq*), and he continues to lie until he is recorded as a liar (*kadhdhab*)."