Sunan Abi Dawud 46
Narrated Abu Hurayrah :
(the Prophet, sal Allaahu alayhi wa sallam ) as saying : Were it not that I might oeverburdern the believers, I would order them to delay the night ('isha ) prayer and use the tooth-stick at the time of every prayer.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ سُفْيَانَ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، يَرْفَعُهُ قَالَ ‏
"‏ لَوْلاَ أَنْ أَشُقَّ، عَلَى الْمُؤْمِنِينَ لأَمَرْتُهُمْ بِتَأْخِيرِ الْعِشَاءِ وَبِالسِّوَاكِ عِنْدَ كُلِّ صَلاَةٍ ‏"‏ ‏.‏