Abu Dharr (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said, "If you want to observe Saum on three days in a month, then fast on the thirteenth, fourteenth and fifteenth of the (lunar) month."[At-Tirmidhi].

Abu Dharr (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said, "If you want to observe Saum on three days in a month, then fast on the thirteenth, fourteenth and fifteenth of the (lunar) month."[At-Tirmidhi].

وعن أبي ذر رضي الله عنه، قال‏:‏ قال رسول الله صلى الله عليه وسلم‏:‏ ‏ "‏إذا صمت من الشهر ثلاثًا، فصم ثلاث عشرة، وأربع عشرة وخمس عشرة‏"‏ رواه الترمذي وقال‏:‏ حديث حسن‏.‏