Clarifying that it does not matter whether the crescent is large or small, for Allah, the Most High, causes it to appear for long enough that people can see it, and if it is cloudy then thirty days should be completed

Abu'l-Bakhtari reported: We went out to perform Umra and when we encamped in the valley of Nakhla, we tried to see the new moon. Some of the people said: It was three nights old, and others (said) that it was two nights old. We then met Ibn 'Abbas and told him we had seen the new moon, but that some of the people said it was three nights old and others that it was two nights old. He asked on which night we had seen it;
and when we told him we had seen it on such and such night, he said the Prophet of Allah ﷺ had said: Verily Allah deferred it till the time it is seen, so it is to be reckoned from the night you saw it.

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا مُحَمَّدُ بْنُ فُضَيْلٍ، عَنْ حُصَيْنٍ، عَنْ عَمْرِو بْنِ، مُرَّةَ عَنْ أَبِي الْبَخْتَرِيِّ، قَالَ خَرَجْنَا لِلْعُمْرَةِ فَلَمَّا نَزَلْنَا بِبَطْنِ نَخْلَةَ - قَالَ - تَرَاءَيْنَا الْهِلاَلَ فَقَالَ بَعْضُ الْقَوْمِ هُوَ ابْنُ ثَلاَثٍ . وَقَالَ بَعْضُ الْقَوْمِ هُوَ ابْنُ لَيْلَتَيْنِ قَالَ فَلَقِينَا ابْنَ عَبَّاسٍ فَقُلْنَا إِنَّا رَأَيْنَا الْهِلاَلَ فَقَالَ بَعْضُ الْقَوْمِ هُوَ ابْنُ ثَلاَثٍ وَقَالَ بَعْضُ الْقَوْمِ هُوَ ابْنُ لَيْلَتَيْنِ . فَقَالَ أَىَّ لَيْلَةٍ رَأَيْتُمُوهُ قَالَ فَقُلْنَا لَيْلَةَ كَذَا وَكَذَا . فَقَالَ إِنَّ رَسُولَ اللَّهِ ﷺ قَالَ " إِنَّ اللَّهَ مَدَّهُ لِلرُّؤْيَةِ فَهُوَ لِلَيْلَةِ رَأَيْتُمُوهُ " .