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
ibnmajah:1647 – al-ʿAbbās b. al-Walīd al-Dimashqī > Marwān b. Muḥammad > al-Haytham b. Ḥumayd > al-ʿAlāʾ b. al-Ḥārith > al-Qāsim Abū ʿAbd al-Raḥman > Muʿāwiyah b. Abū Sufyān > al-Minbar

“The Messenger of Allah ﷺ used to say from the pulpit, before the month of Ramadan: ‘Fasting will begin on such and such a day, but we are going to start fasting earlier, so whoever wants to start fasting earlier (i.e., in Sha’ban), let him do so, and whoever wants to wait until Ramadan begins, let him do so.’”  

ابن ماجة:١٦٤٧ – حَدَّثَنَا الْعَبَّاسُ بْنُ الْوَلِيدِ الدِّمَشْقِيُّ حَدَّثَنَا مَرْوَانُ بْنُ مُحَمَّدٍ حَدَّثَنَا الْهَيْثَمُ بْنُ حُمَيْدٍ حَدَّثَنَا الْعَلاَءُ بْنُ الْحَارِثِ عَنِ الْقَاسِمِ أَبِي عَبْدِ الرَّحْمَنِ

أَنَّهُ سَمِعَ مُعَاوِيَةَ بْنَ أَبِي سُفْيَانَ عَلَى الْمِنْبَرِ يَقُولُ كَانَ رَسُولُ اللَّهِ ﷺ يَقُولُ عَلَى الْمِنْبَرِ قَبْلَ شَهْرِ رَمَضَانَ الصِّيَامُ يَوْمَ كَذَا وَكَذَا وَنَحْنُ مُتَقَدِّمُونَ فَمَنْ شَاءَ فَلْيَتَقَدَّمْ وَمَنْ شَاءَ فَلْيَتَأَخَّرْ  

See similar narrations below:

Collected by Ṭabarānī
tabarani:16991 – Ibrāhīm b. Muḥammad b. ʿIrq al-Ḥimṣī > Yaḥyá b. ʿUthmān > Marwān b. Muḥammad al-Ṭāṭarī > al-Haytham b. Ḥumayd > al-ʿAlāʾ b. al-Ḥārith > al-Qāsim Abū ʿAbd al-Raḥman > Muʿāwiyah

[Machine] He heard Muawiyah say, "Indeed, the Messenger of Allah ﷺ used to start fasting one day before Ramadan and would say, 'Verily, the fasting of a day is like so and so, and we are preemptive. So whoever wishes to begin fasting, let him begin, and whoever wishes to leave it, let him leave.'"  

الطبراني:١٦٩٩١ – حَدَّثَنَا إِبْرَاهِيمُ بْنُ مُحَمَّدِ بْنِ عِرْقٍ الْحِمْصِيُّ ثنا يَحْيَى بْنُ عُثْمَانَ ثنا مَرْوَانُ بْنُ مُحَمَّدٍ الطَّاطَرِيُّ ثنا الْهَيْثَمُ بْنُ حُمَيْدٍ عَنِ الْعَلَاءِ بْنِ الْحَارِثِ ثنا الْقَاسِمُ أَبُو عَبْدِ الرَّحْمَنِ

أَنَّهُ سَمِعَ مُعَاوِيَةَ يَقُولُ إِنَّ رَسُولَ اللهِ ﷺ كَانَ يَقُومُ عَلَى الْمِنْبَرِ قَبْلَ رَمَضَانَ بِيَوْمٍ وَيَقُولُ «إِنَّ الصِّيَامَ يَوْمُ كَذَا وَكَذَا وَنَحْنُ مُتَقَدِّمُونَ فَمَنْ أَحَبَّ أَنْ يَتَقَدَّمَ فَلْيَتَقَدَّمْ وَمَنْ أَحَبَّ أَنْ يَتْرُكَ فَلْيَتْرُكْ»