תּלמוד אויף דברים 10:10

One verse says, "And I sat [va'eshev] on the mountain" (Deuteronomy 9:9), and another verse says, "And I stood on the mountain"(Deuteronomy 10:10): Rav says: He [Moses] stood when he learned and sat while he repeated [what he had learned]. R. Hanina said: He was neither sitting nor standing, but stooping. R. Yohanan said: Sitting here means only "staying", as it says, "And you stayed [teshvu] in Kadesh many days" (Deuteronomy 1:46). Rava said: The easy things [he learned] standing and the hard ones sitting

R. Hannin said in the name of R. Hannina : Whoever prolongs his prayer, his prayer will not return empty. Whence have we this ? From Moses our teacher ; as it is said, "And I prayed unto the Lord" (Deut. ix. 26), and it is afterwards written, "[Now I stayed in the mount... forty days and forty nights ;] and the Lord hearkened unto me that time also" (ibid. x. 10).