"‏ إِنَّ اللَّهَ هُوَ السَّلاَمُ فَإِذَا قَعَدَ أَحَدُكُمْ فِي الصَّلاَةِ فَلْيَقُلِ التَّحِيَّاتُ لِلَّهِ وَالصَّلَوَاتُ وَالطَّيِّبَاتُ السَّلاَمُ عَلَيْكَ أَيُّهَا النَّبِيُّ وَرَحْمَةُ اللَّهِ وَبَرَكَاتُهُ السَّلاَمُ عَلَيْنَا وَعَلَى عِبَادِ اللَّهِ الصَّالِحِينَ فَإِذَا قَالَهَا أَصَابَتْ كُلَّ عَبْدٍ لِلَّهِ صَالِحٍ فِي السَّمَاءِ وَالأَرْضِ أَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ وَأَشْهَدُ أَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ ثُمَّ يَتَخَيَّرُ مِنَ الْمَسْأَلَةِ مَا شَاءَ ‏"

While observing prayer behind the Messenger of Allah (ﷺ) we used to recite: Peace be upon Allah, peace be upon so and so. One day the Messenger of Allah (ﷺ) said to us: Verily Allah is Himself Peace. When any one of you sits during the prayer, he should say: All services rendered by words, by acts of worship, and all good things are due to Allah. Peace be upon you, O Prophet, and Allah's mercy and blessings. Peace be upon us and upon Allah's upright servants, for when he says this it reaches every upright servant in the heavens and the earth. (And say further): I testify that there is no god but Allah and I testify that Muhammad is His servant and Messenger. Then he may choose any supplication which pleases him and offer it.