Is it permissible for a Muslim to donate the reward of his fasting to someone untrustworthy in narrating hadith, such as Yazid al-Raqashi, who cried at the time of death saying: "Who will pray for you, Yazid, when you die? And who will fast for you?"?

Yazid ibn Aban al-Raqashi was among the righteous ascetics, but he was weak in narrating hadith. There are accounts of his asceticism and admonitions from which one can benefit. It was said of him: "He is a righteous man, but his hadith is worthless," and "He was among the best worshippers of Allah, one of those who wept at night." Donating the reward of fasting to him will benefit him, Allah willing. However, it is more appropriate for you to keep the reward of your deeds for yourself and supplicate for him with mercy. His admonition reminds us of the importance of rectifying our deeds and presenting what will benefit us after death.