عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((إِذَا صَلَّى أَحَدُكُمْ فَلَا يَدْرِي كَمْ صَلَّى فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ، وَإِذَا جَاءَ أَحَدَكُمُ الشَّيْطَانُ فَقَالَ إِنَّكَ قَدْ أَحْدَثْتَ فَلْيَقُلْ كَذَبْتَ إِلَّا مَا وَجَدَ رِيحَهُ بِأَنْفِهِ أَوْ سَمِعَ صَوْتَهُ بِأُذُنِهِ))
Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings be upon him) said: When any one of you prays and forgets to such an extent that he does not know how much he has prayed, then he should perform two prostrations while sitting. And when Satan comes to someone and says, "You have broken your ablution," he should say to him, "You have lied," unless he perceives a smell from his nose or hears a sound with his ear.