Prohibition to eat on the day of doubt (whether the crescent moon could be sighted)
TIRMIDHI 686:
from Ṣilah b. Zufar —
We were with Ammar b. Yasir when a roasted sheep was brought and he said: "Eat." Someone among the people said: "I am fasting." So Ammar said: "Whoever fasts on a day in which there is doubt, then he has disobeyed Abu al-Qasim ﷺ."
الترمذي ٦٨٦:
عن صله بن زفر —
كُنَّا عِنْدَ عَمَّارِ بْنِ يَاسِرٍ فَأُتِيَ بِشَاةٍ مَصْلِيَّةٍ فَقَالَ كُلُوا فَتَنَحَّى بَعْضُ الْقَوْمِ فَقَالَ إِنِّي صَائِمٌ فَقَالَ عَمَّارٌ مَنْ صَامَ الْيَوْمَ الَّذِي يَشُكُّ فِيهِ النَّاسُ فَقَدْ عَصَى أَبَا الْقَاسِمِ ﷺ