Brotherhood of the Cross and Star members kneel, bow and knock their head on the ground three successive times in reverence to the Holy Trinity God ((The Father, Son and Holy Spirit), before and after prayers or at any time, place or occasion whenever the spirit directs. Knocking of head is a very vital and effective part of communication with God; it is akin to a dialing tone or knocking on the door before going in.
Matthew 26:39 [KJV]  And he went a little further, and fell on his face, and prayed, saying, O my Father, if it be possible, let this cup pass from me: nevertheless not as I will, but as thou wilt.
1Corinthians 14:25 [KJV]  And thus are the secrets of his heart made manifest; and so falling down on his face he will worship God, and report that God is in you of a truth.
Rev 7:11 [KJV]  And all the angels stood round about the throne, and about the elders and the four beasts, and fell before the throne on their faces, and worshipped God