Bulugh al-Maram 1 The Book of Purification كتاب الطهارة 170

وَفِي رِوَايَةٍ لِلْبُخَارِيِّ: { وَتَوَضَّئِي لِكُلِّ صَلَاةٍ } وَهِيَ لِأَبِي دَاوُدَ وَغَيْرِهِ مِنْ وَجْهٍ آخَرَ.

In another version by Al-Bukhari, he (صلى الله عليه وسلم) said: “And perform ablution for every Salat (prayer)”. Abu Dawud and others transmitted a similar narration.