Man Lā Yaḥḍuruh al-Faqīh
Hadith 3511922 - سُئِلَ أَمِيرُ اَلْمُؤْمِنِينَ عَلَيْهِ اَلسَّلاَمُ : عَنِ اَلْيَوْمِ اَلْمَشْكُوكِ فِيهِ فَقَالَ «لَأَنْ أَصُومَ يَوْماً مِنْ شَعْبَانَ أَحَبُّ إِلَيَّ مِنْ أَنْ أُفْطِرَ يَوْماً مِنْ شَهْرِ رَمَضَانَ ».
Hadith.1922 - Commander of the Faithful Imam Ali ibn Abi Talib (as) was asked about the day of doubt (the day when it is uncertain whether it is the last day of Sha'ban or the first day of Month of Ramadan).
Imam (as) said: "Fasting one day from Sha'ban is more beloved to me than breaking my fast for one day in the Month of Ramadan."