Q. Why do we stand when we sing?
And the Levites, of the sons of the Kohathites, and of the sons of the Korhites, rise to give praise to Jehovah, God of Israel, with a loud voice on high. II Chronicles 20:19 (YLT)
Ye that stand in the house of the LORD, in the courts of the house of our God. Praise the LORD; for the LORD is good: sing praises unto his name; for it is pleasant.
Psalms 135:2-3 (KJV)
Q. Why do we clap our hands?
O, CLAP your hands, all you peoples! Shout to God with the voice of triumph and songs of joy! Psalms 47:1 (Amplified)
Q. Why do we lift our hands?
Lift up your hands to the sanctuary and bless the LORD. Psalms 134:2 (ASB)
Thus will I bless thee while I live: I will lift up my hands in thy name. Psalms 63:4 (KJV)
I want men everywhere to lift up holy hands in prayer, without anger or disputing.
I Timothy 2:8 (NIV)
Q. Why do we bow down and kneel?
Come, let us bow down in worship, let us kneel before the LORD our Maker;
Psalms 95:6 (NIV)