Acts 20:36

He kneeled down; a posture of great humility, becoming prayer, and frequently used on such occasions, especially in a time of great trouble and distress. Although bodily exercise alone do not profit, 1 Timothy 4:8, yet we may, and must on occasion, in prayer bow the knee, lift up the hand and eye;

1. Because it is a reasonable thing to give our bodies in his service to God that made them.

2. By this we may show that we are not ashamed to serve and own God before men. And:

3. These outward signs do sometimes stir up our own and others devotion.