The Rewards & Punishments of Deeds · Hadith 258 (#Ḥadīth #2)

أَبِی ره قَالَ حَدَّثَنِی أَحْمَدُ بْنُ إِدْرِیسَ قَالَ حَدَّثَنِی مُحَمَّدُ بْنُ أَحْمَدَ قَالَ حَدَّثَنَا مُوسَی بْنُ عُمَیْرٍ عَنْ عَلِیِّ بْنِ الْحَکَمِ عَنْ أَحْمَدَ بْنِ زَیْدٍ عَنْ مُوسَی بْنِ جَعْفَرٍ ع قَالَ: مَنْ صَامَ أَوَّلَ یَوْمٍ مِنَ الْعَشْرِ عَشْرِ ذِی الْحِجَّهِ کَتَبَ اللَّهُ لَهُ صَوْمَ ثَمَانِینَ شَهْراً فَإِنْ صَامَ التِّسْعَ کَتَبَ اللَّهُ لَهُ صَوْمَ الدَّهْرِ.

2. My father said: it was narrated to me by Ahmad b. Idris who said it was narrated to me by Muhammad b. Ahmad who said it was narrated to us by Musa b. ’Umayr from Ali b. al-Hakam from Ahmad b. Zayd from Musa b. Ja’far who said: “One who fasts on the first day of Zilhajj Almighty Allah would note down the reward of the fasts of eighty months for him. If he observes fast for nine days Allah would note the reward of fasts of an age for him.”

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).