Hadith: Allāhumma bā‘id bayni wa bayna khatāyāy kama bā‘dta bayna al-mashriqi wa al-maghrib

عَنْ أَبِي هُرَيْرَةَ رضي الله عنه قَالَ:
كَانَ رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، إِذَا كَبَّرَ فِي الصَّلَاةِ، سَكَتَ هُنَيَّةً قَبْلَ أَنْ يَقْرَأَ، فَقُلْتُ: يَا رَسُولَ اللهِ بِأَبِي أَنْتَ وَأُمِّي أَرَأَيْتَ سُكُوتَكَ بَيْنَ التَّكْبِيرِ وَالْقِرَاءَةِ، مَا تَقُولُ؟ قَالَ «أَقُولُ: اللهُمَّ بَاعِدْ بَيْنِي وَبَيْنَ خَطَايَايَ كَمَا بَاعَدْتَ بَيْنَ الْمَشْرِقِ وَالْمَغْرِبِ، اللهُمَّ نَقِّنِي مِنْ خَطَايَايَ كَمَا يُنَقَّى الثَّوْبُ الْأَبْيَضُ مِنَ الدَّنَسِ، اللهُمَّ اغْسِلْنِي مِنْ خَطَايَايَ بِالثَّلْجِ وَالْمَاءِ وَالْبَرَدِ».
[صحيح] - [متفق عليه] - [صحيح مسلم: 598]

Abu Hurayrah (may Allah be pleased with him) reported:
When the Messenger of Allah (may Allah's peace and blessings be upon him) made Takbīr in the prayer, he would remain silent a while before reciting. I said: O Messenger of Allah, may my father and mother ransom you! Have you seen your silence between Takbīr and the recitation? What is it that you say? He said: "I say: Allāhumma bā‘id bayni wa bayna khatāyāy kama bā‘dta bayna al-mashriqi wa al-maghrib. Allāhumma naqqini min khatāyāy kama yunaqqa ath-thawbu al-abyadu min ad-danas. Allāhumma ighsilni min khatāyāy bith-thalji wa al-mā’i wa al-barad (O Allah, distance me from my sins as You have distanced the east from the west. O Allah, purify me from my sins as a white garment is purified from dirt. O Allah, wash out my sins with water, snow, and hail)."
[Authentic hadith] - [Narrated by Bukhari & Muslim] - [Sahih Muslim - 598]

Explanation

On making Takbīr to commence the prayer, the Prophet (may Allah's peace and blessings be upon him) would take a brief pause before reciting Surat al-Fātihah. During this pause, he would start his prayer by reciting some supplications. Among the supplications reported in this regard is his saying: "Allāhumma bā‘id bayni wa bayna khatāyāy kama bā‘dta bayna al-mashriqi wa al-maghrib*. Allāhumma naqqini min khatāyāy kama yunaqqa ath-thawbu al-abyadu min ad-danas. Allāhumma ighsilni min khatāyāy bith-thalji wa al-mā’i wa al-barad (O Allah, distance me from my sins as You have distanced the east from the west. O Allah, purify me from my sins as a white garment is purified from dirt. O Allah, wash out my sins with water, snow, and hail)." He supplicates Allah Almighty to keep him far from sins, by helping him not to commit them, in such a way that makes it impossible for them to meet, just as the East and the West can never meet; and to purify him and remove such sins if he commits them, as filth is removed from the white garment; and to wash him from his sins and cool off its flames and heat with such cold purifiers: water, snow, and hail.