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.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
bayhaqi:7921 – Abū Saʿīd > Abū al-ʿAbbās > al-Rabīʿ > Qāl al-Shāfiʿī Ḥikāyah > Abū Muʿāwiyah > al-Aʿmash > ʿUmārah > ʿAbd al-Raḥman b. Yazīd > ʿAbdullāh > Ibn Masʿūd > Aḥadukum Bi-al-Khiyār Mā Lam Yaʾkul or Yashrab > al-Shāfiʿī > / al-ʿIrāqiyyīn Lā Yarawn Hadhā Yazʿumūn

[Machine] He is not considered a fasting person until he intends to fast before the sunset. As for us, we say that the voluntary fast is whenever one intends to fast.  

البيهقي:٧٩٢١ – وَأَخْبَرَنَا أَبُو سَعِيدٍ ثنا أَبُو الْعَبَّاسِ أنبأ الرَّبِيعُ قال قَالَ الشَّافِعِيُّ حِكَايَةً عَنْ أَبِي مُعَاوِيَةَ عَنِ الْأَعْمَشِ عَنْ عُمَارَةَ عَنْ عَبْدِ الرَّحْمَنِ بْنِ يَزِيدَ عَنْ عَبْدِ اللهِ هُوَ ابْنُ مَسْعُودٍ قَالَ أَحَدُكُمْ بِالْخِيَارِ مَا لَمْ يَأْكُلْ أَوْ يَشْرَبْ وَقَالَ الشَّافِعِيُّ هُمْ يَعْنِي الْعِرَاقِيِّينَ لَا يَرَوْنَ هَذَا يَزْعُمُونَ

أَنَّهُ لَا يَكُونُ صَائِمًا حَتَّى يَنْوِيَ الصَّوْمَ قَبْلَ زَوَالِ الشَّمْسِ وَأَمَّا نَحْنُ فَنَقُولُ الْمُتَطَوِّعُ بِالصَّوْمِ مَتَى شَاءَ نَوَى الصِّيَامَ