Since Hajj and Umrah are symbolic expressions of devotion to Allah i.e. One is ready to offer his life and wealth for Him when he is called for this. Hajj and umrah are symbolic manifestations of this offering. Both are an embodiment of the same reality. The only difference is that the latter is compact and the former more comprehensive in which the objective for which life and wealth are offered becomes very evident.
All the rituals of Hajj and Umra portray these symbols in some way. Among these rituals are Animal sacrifice which symbolizes that one is willing to sacrifice one’s life for the Almighty and shaving the head which symbolizes that the sacrifice has been presented and a person with the mark of obedience and eternal servitude to the Almighty can now return to his home.
Shaving the head is an ancient tradition of the religion of Abraham (sws). Consequently, this law has been stated in the Torah that a person who has been offered and devoted to God should not shave his head until the days of the vow are complete:
During this entire period of his vow of separation no razor may be used on his head. He must be holy until the period of his separation to the Lord is over; he must let the hair of his head grow long. (Numbers, 5:6)
Now this is the law for the Nazirite when the period of his separation is over. He is to be brought to the entrance to the Tent of Meeting … then at the entrance to the Tent of Meeting, the Nazirite must shave off the hair that he dedicated. He is to take the hair and put it in the fire that is under the sacrifice of the fellowship offering.(Numbers, 6:13, 18)