Sahih Muslim Book - 4, Hadith - 897

حَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ وَعُثْمَانُ بْنُ أَبِي شَيْبَةَ وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ قَالَ إِسْحَاقُ أَخْبَرَنَا وَقَالَ الْآخَرَانِ حَدَّثَنَا جَرِيرٌ عَنْ مَنْصُورٍ عَنْ أَبِي وَائِلٍ عَنْ عَبْدِ اللَّهِ قَالَ كُنَّا نَقُولُ فِي الصَّلَاةِ خَلْفَ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ السَّلَامُ عَلَى اللَّهِ السَّلَامُ عَلَى فُلَانٍ فَقَالَ لَنَا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ذَاتَ يَوْمٍ إِنَّ اللَّهَ هُوَ السَّلَامُ فَإِذَا قَعَدَ أَحَدُكُمْ فِي الصَّلَاةِ فَلْيَقُلْ التَّحِيَّاتُ لِلَّهِ وَالصَّلَوَاتُ وَالطَّيِّبَاتُ السَّلَامُ عَلَيْكَ أَيُّهَا النَّبِيُّ وَرَحْمَةُ اللَّهِ وَبَرَكَاتُهُ السَّلَامُ عَلَيْنَا وَعَلَى عِبَادِ اللَّهِ الصَّالِحِينَ فَإِذَا قَالَهَا أَصَابَتْ كُلَّ عَبْدٍ لِلَّهِ صَالِحٍ فِي السَّمَاءِ وَالْأَرْضِ أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَأَشْهَدُ أَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ ثُمَّ يَتَخَيَّرُ مِنْ الْمَسْأَلَةِ مَا شَاءَ.

It was narrated that 'Abdullah said: "When we offered Salat behind the Messenger of Allah (s.a.w), we used to say: 'Peace (Salam) be upon Allah, peace be upon so-and-so.' The Messenger of Allah (s.a.w) said to us one day: 'Allah is As-Salam, so when one of you sits in prayer (during Qa'ida), let him say: ''At-Tahiyyatu Lillahi was-salawatu wat-tayyibat; as-salamu 'alayka ayyuhan-nabiyyu wa rahmatullahi wa barakatuhu; as-salamu 'alaina wa 'ala 'ibad-illahis-salihin (All compliments, prayers and good words are due to Allah; peace be upon you, O Prophet, and the mercy of Allah and His blessings; peace be upon us and upon the righteous slaves of Allah). For if you say that it will reach every righteous slave in the heavens and on earth. (Then say:) "Ashhadu an Ia ililha illallah, wa ashhadu anna Muhammadan 'abduhu wa Rasuluhu (I bear witness that there is none worthy of worship except Allah and I bear witness that Muhammad is His slave and Messenger)." Then let him choose whatever supplications he wishes.'"