The times we fasted twenty-nine days with the Prophet ﷺ were more than the times we fasted thirty days with him.
حدثنا أحمد بن منيع عن ابن أبي زائدة عن عيسى بن دينار عن أبيه عن عمرو بن الحارث بن أبي ضرار
لما صمنا مع النبي ﷺ تسعا وعشرين أكثر مما صمنا معه ثلاثين
Its isnad is sahih. Tirmidhi transmitted it in the chapter on fasting, in the section on what has been mentioned regarding the month sometimes being twenty-nine days, hadith no. 689, from Ahmad bin Mani, through this same chain.Yahya bin Zakariya bin Abu Zaida stated explicitly that he heard it directly.