[Machine] that the Messenger of Allah ﷺ commanded to perform ablution (wudu) for every prayer, whether in a state of purity or not, and when this became difficult for them, he commanded the use of siwak (toothstick) for every prayer. Ibn Umar saw that it gave him strength, so he never left ablution for any prayer. This is the narration of Ahmad bin Khalid Al-Wahbi, and Saeed mentioned it in his narration from Ubaidullah bin Abdullah, who said that when this became difficult for them, Abu Dawood Ibrahim bin Saad said.  

أَنَّ رَسُولَ اللهِ ﷺ أَمَرَ بِالْوُضُوءِ عِنْدَ كُلِّ صَلَاةٍ طَاهِرًا أَوْ غَيْرَ طَاهِرٍ فَلَمَّا شَقَّ ذَلِكَ عَلَيْهِ أَمَرَ بِالسِّوَاكِ لِكُلِّ صَلَاةٍ فَكَانَ ابْنُ عُمَرَ يَرَى أَنَّ بِهِ قُوَّةً فَكَانَ لَا يَدَعُ الْوُضُوءَ لِكُلِّ صَلَاةٍ لَفْظُ حَدِيثِ أَحْمَدَ بْنِ خَالِدٍ الْوَهْبِيِّ وَقَالَ سَعِيدٌ فِي حَدِيثِهِ عَنْ عُبَيْدِ اللهِ بْنِ عَبْدِ اللهِ قَالَ فَلَمَّا شَقَّ ذَلِكَ عَلَيْهِمْ قَالَ أَبُو دَاوُدَ إِبْرَاهِيمُ بْنُ سَعْدٍ