Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: At first, we did not know what we should recite in prayer, so we used to say: Peace be upon Sayyiduna Jibreel, peace be upon Sayyiduna Mika'il. Then the Prophet (peace and blessings of Allah be upon him) taught us. He said: Allah Himself is the Giver of peace. When you sit after performing two rak'ahs, recite this: "All verbal, physical, and financial acts of worship are exclusively for Allah. O Prophet, peace be upon you. May Allah's mercy and His blessings descend upon you. Peace be upon us and upon all the righteous servants of Allah." Abu Wa'il narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) in his narration these words: (The Prophet, peace and blessings of Allah be upon him, said) "When you recite these words, this peace will reach every close angel, every sent prophet, and every righteous servant. (You should also recite:) I bear witness that there is no deity except Allah, and I bear witness that Sayyiduna Muhammad (peace and blessings of Allah be upon him) is His servant and His Messenger."
Hadith Referenceصحیح ابن حبان / كتاب الصلاة / 1950
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «صحيح أبي داود» (890).فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط البخاري، أبو الأحوص: هو عوف بن مالك الجشمي.