Mishkat al-Masabih 3 Purification كتاب الطهارة 12

وَعَنِ ابْنِ عُمَرَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ تَوَضَّأَ عَلَى طُهْرٍ كُتِبَ لَهُ عَشْرُ حَسَنَاتٍ» . رَوَاهُ التِّرْمِذِيُّ

Ibn ‘Umar reported God’s messenger as saying, “He who performs ablution when in a state of purity will have ten blessings recorded for him.” Tirmidhi transmitted it.