Hamlet 3.3 "Heart with Strings of Steel”

The transcript describes a character whose heart and knee tendons have become as hard as steel, preventing him from feeling remorse or kneeling in prayer. He wishes for them to be as soft as a baby's, enabling repentance and prayer. At this moment, Hamlet enters and sees Claudius kneeling in prayer.

What action does Hamlet want to perform with his knees?

Who does Hamlet observe kneeling in prayer?