Sunan at-Tirmithiy كتاب الصلاة باب ما جاء كم فرض الله على عباده من الصلوات

حَدَّثَنَا مُحَمَّدُ بْنُ يَحْيَى النَّيْسَابُورِىُّ حَدَّثَنَا عَبْدُ الرَّزَّاقِ أَخْبَرَنَا مَعْمَرٌعَنِ الزُّهْرِىِّ عَنْ أَنَسِ بْنِ مَالِكٍ قَالَ فُرِضَتْ عَلَى النَّبِىِّ صلى الله عليه وسلم لَيْلَةَ أُسْرِىَ بِهِ الصَّلَوَاتُ خَمْسِينَ ثُمَّ نُقِصَتْ حَتَّى جُعِلَت ْخَمْسًا ثُمَّ نُودِىَ يَا مُحَمَّدُ إِنَّهُ لاَ يُبَدَّلُ الْقَوْلُ لَدَىَّ وَإِنَّ لَكَ بِهَذِهِ الْخَمْسِ خَمْسِينَ. قَالَ وَفِى الْبَابِ عَنْ عُبَادَةَ بْنِ الصَّامِتِ وَطَلْحَةَ بْنِ عُبَيْدِ اللَّهِ وَأَبِى ذَرٍّ وَأَبِى قَتَادَةَ وَمَالِكِ بْنِ صَعْصَعَةَ وَأَبِى سَعِيدٍ الْخُدْرِىِّ. قَالَ أَبُو عِيسَى حَدِيثُ أَنَسٍ حَدِيثٌ حَسَنٌ صَحِيحٌ.
Fifty prayers were prescribed on the Prophet, peace and blessings of God be upon him, when he was taken on the Night Journey (1). They were then [gradually] reduced until they were five. Then he was called, "Muhammad, indeed My word (decree) is not changed, and Indeed, you have for these five the recorded merits of fifty prayers." Footnote (1): (al-isrā'): the Night Journey of prophet Muhammad from Makkah to Jerusalem