The last two stanzas are a kind of conclusion. An analysis of each stanza in conjunction with an analysis of the poem's structure can give us the answer to this question. The first is that you are bowing your head so that the sun will not hurt your eyes. Another possibility is that you are dead, your body wasting away out in the desert. The third possibility is that you are praying.
Death is often a symbol for entering into eternity.
Finally, God is a sphere with its center everywhere but its circumference is nowhere. It has omnipotence, omnipresence, and omniscience. So God, too, is a symbol for eternity. So the first line illustrates submission, willing or unwilling, to death and eternity and the measure of eternity, time. A number of times a day, Muslims must fall to their knees and pray in the direction of Mecca.