Arabic Text
وَحَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا عُبَيْدُ اللَّهِ، بِهَذَا الإِسْنَادِ وَقَالَ " فَإِنْ غُمَّ عَلَيْكُمْ فَاقْدِرُوا ثَلاَثِينَ " . نَحْوَ حَدِيثِ أَبِي أُسَامَةَ .
English Translation
This hadith is narrated on the authority of 'Ubaidullah with the same chain of transmitters, and he said: If (the sky) is cloudy for you, then calculate thirty days (for the month of Ramadan).
This hadith is from Sahih Muslim, one of the most rigorously authenticated collections in Islamic scholarship. No editorial opinion is added.