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:7667 – Abū ʿAbdullāh al-Ḥāfiẓ > Yūsuf b. Isḥāq b. Yaʿqūb al-Sūsī > Aḥmad b. Salamah > Isḥāq b. Ibrāhīm > Yaḥyá b. Ādam

[Machine] He used to say that this verse was revealed in reference to the zakat of Ramadan.  

البيهقي:٧٦٦٧ – أَخْبَرَنَا أَبُو عَبْدِ اللهِ الْحَافِظُ ثنا يُوسُفُ بْنُ إِسْحَاقَ بْنِ يَعْقُوبَ السُّوسِيُّ ثنا أَحْمَدُ بْنُ سَلَمَةَ ثنا إِسْحَاقُ بْنُ إِبْرَاهِيمَ ثنا يَحْيَى بْنُ آدَمَ ثنا أَبُو حَمَّادٍ الْحَنَفِيُّ عَنْ عُبَيْدِ اللهِ بْنِ عُمَرَ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ

أَنَّهُ كَانَ يَقُولُ نَزَلَتْ هَذِهِ الْآيَةُ {قَدْ أَفْلَحُ مَنْ تَزَكَّى وَذَكَرَ اسْمَ رَبِّهِ فَصَلَّى} [الأعلى 15] فِي زَكَاةِ رَمَضَانَ  

See similar narrations below:

Collected by Bayhaqī
bayhaqi:7668 – Abū al-Ḥasan b. ʿAbdān > Aḥmad b. ʿUbayd al-Ṣaffār > Jaʿfar b. Aḥmad b. Yāsīn > Muḥammad b. Isḥāq al-Musayyabī > ʿAbdullāh b. Nāfiʿ > Kathīr b. ʿAbdullāh al-Muzanī from his father from his grandfather

[Machine] The Messenger of Allah ﷺ was asked about his saying, "Indeed, he has succeeded who purifies himself and mentions the name of his Lord and prays." [Surah Al-A'la, verse 15] He said, "It is the Zakat al-Fitr."  

البيهقي:٧٦٦٨ – وَأَخْبَرَنَا أَبُو الْحَسَنِ بْنُ عَبْدَانَ أنبأ أَحْمَدُ بْنُ عُبَيْدٍ الصَّفَّارُ ثنا جَعْفَرُ بْنُ أَحْمَدَ بْنِ يَاسِينَ ثنا مُحَمَّدُ بْنُ إِسْحَاقَ الْمُسَيَّبِيُّ ثنا عَبْدُ اللهِ بْنُ نَافِعٍ عَنْ كَثِيرِ بْنِ عَبْدِ اللهِ الْمُزَنِيِّ عَنْ أَبِيهِ عَنْ جَدِّهِ

أَنَّ رَسُولَ اللهِ ﷺ سُئِلَ عَنْ قَوْلِهِ {قَدْ أَفْلَحَ مَنْ تَزَكَّى وَذَكَرَ اسْمَ رَبِّهِ فَصَلَّى} [الأعلى 15] قَالَ هِيَ زَكَاةُ الْفِطْرِ