The Song of Ascents: Behold, bless the Lord, all servants of the Lord who stand in the house of the Lord at night. What is "at night"? Rabbi Yochanan said, "These are the scholars who study Torah at night; I consider them as if they are engaged in the work [of the Temple]." (Chronicles II 3:3) Forever may this be for Israel. Rav Giddel said in the name of Rav, "This refers to the altar that was built, and Michael, the great prince, stands and offers sacrifices upon it."
Rabbi Yochanan said, "These are the scholars who engage in the study of the laws of the Temple service; I consider them as if the Temple was built in their time." Raise your hands in holiness and bless the Lord. Ten things were said in the cup of blessing, raised up from the ground a handbreadth. Rabbi Chanina bar Papa said, "What is the meaning of 'raise your hands in holiness'?
Rabbi Shimon ben Pazi said, 'Any priest who has not washed his hands is forbidden to lift his palms, as it is said, 'Raise your hands in holiness and bless the Lord.'" "Three knocks they are: Knock once for semicha (laying of hands) and then for shechita (slaughtering) (Leviticus 1:4-5). Knock once for washing hands and recite the blessing, as it is said, 'Lift up your hands to the sanctuary and bless the Lord' (Psalm 134:2).
Knock once for redemption and pray, 'May the words of my mouth and the meditation of my heart be acceptable before You, O Lord, my Rock and my Redeemer' (Psalm 19:15). What is written thereafter? 'The Lord will answer you in the day of trouble' (Psalm 20:2). Rabbi Yosei bar Bon said: Whoever knocks for semicha and shechita, the issue of piggul (invalidated sacrifice due to improper intention) does not apply to that sacrifice.
Whoever knocks for washing hands and recites the blessing, the Satan does not accuse him during that meal. And whoever knocks for redemption and prayer, the Satan does not accuse him on that day."