Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
bayhaqi:7949Abū Bakr b. Fūrak > ʿAbdullāh b. Jaʿfar > Yūnus b. Ḥabīb > Abū Dāwud al-Ṭayālisī > Abū ʿAwānah > Simāk > ʿIkrimah > Ibn ʿAbbās

[Machine] "That the Messenger of Allah ﷺ said: Fast upon sighting the crescent of Ramadan and break the fast upon sighting the crescent of Shawwal. However, if a cloud or fog comes between you and the crescent, then complete thirty days of Sha'ban and do not begin Ramadan with a day of fasting from Sha'ban. And it is as if he mentioned the ruling for both sides, and each of them narrated one of the two sides."  

البيهقي:٧٩٤٩أَخْبَرَنَاهُ أَبُو بَكْرِ بْنُ فُورَكٍ أنبأ عَبْدُ اللهِ بْنُ جَعْفَرٍ ثنا يُونُسُ بْنُ حَبِيبٍ ثنا أَبُو دَاوُدَ الطَّيَالِسِيُّ ثنا أَبُو عَوَانَةَ عَنْ سِمَاكٍ عَنْ عِكْرِمَةَ عَنِ ابْنِ عَبَّاسٍ

أَنَّ رَسُولَ اللهِ ﷺ قَالَ صُومُوا رَمَضَانَ لِرُؤْيَتِهِ وَأَفْطِرُوا لِرُؤْيَتِهِ فَإِنْ حَالَ بَيْنَكُمْ وَبَيْنَهُ غَمَامَةٌ أَوْ ضَبَابَةٌ فَأَكْمِلُوا شَهْرَ شَعْبَانَ ثَلَاثِينَ وَلَا تَسْتَقْبِلُوا رَمَضَانَ بِصَوْمِ يَوْمٍ مِنْ شَعْبَانَ وَكَأَنَّهُ ذَكَرَ الْحُكْمَ فِي الطَّرَفَيْنِ جَمِيعًا فَرَوَى كُلُّ وَاحِدٍ مِنْهُمَا أَحَدَ طَرَفَيْهِ