"and his hands were steadfast until the sun set": We are hereby apprised that he was (occupied with prayer and) fasting (until sunset). These are the words of R. Yehoshua. R. Eliezer Hamodai sys: The sin (of Israel) weighed down Moses' hands and he could not support them. What did he do? He turned to the deeds of the patriarchs, viz. "and they took a stone and they placed it beneath him": "and they took a stone"—the deeds of the patriarchs (viz. (Genesis 49:2)4). "and he sat upon it (feminine)—the deeds of the matriarchs. ...