1. "When Jethro, the priest of Midian, Moses's father-in-law, heard of all that Hashem had done for Moses..." (Shemot 18:1). Rabbi Chizkiyah opened the discussion, saying: "And Aaron lifted up his hands" (Vayikra 9:22). "His hands" is spelled without Yud, thus meaning one hand only. And this is the reason, one should lift up his right hand above his left hand. And we have already explained this secret.