And complete the Hajj or ‘umra in the service of Allah. But if ye are prevented (From completing it), send an offering for sacrifice, such as ye may find, and do not shave your heads until the offering reaches the place of sacrifice. And if any of you is ill, or has an ailment in his scalp, (Necessitating shaving), (He should) in compensation either fast, or feed the poor, or offer sacrifice; and when ye are in peaceful conditions (again), if any one wishes to continue the ‘umra on to the hajj, He must make an offering, such as he can afford, but if he cannot afford it, He should fast three days during the hajj and seven days on his return, Making ten days in all. This is for those whose household is not in (the precincts of) the Sacred Mosque. And fear Allah, and know that Allah Is strict in punishment.
Yahiya Emerick writes:
There are two types of pilgrimage: the major pilgrimage, or Hajj; and the minor pilgrimage, or ‘Umrah. The Hajj is the once-in-a-lifetime pilgrimage to Mecca that all Muslims must undertake at least once in his or her life if they are of sound mind, past puberty, fit enough for the journey and financially able. It is performed in the month of Dhul-Hijjah only. The non-binding ‘Umrah can be performed at any time during the year and is counted as a pious act. Most pilgrims combine both types together by arriving in Mecca before the start of the Hajj, performing their ‘Umrah and then staying on to complete the Hajj. While in Mecca the pilgrims participate in a number of rituals, both within the city and out in the countryside, that enable them to rededicate their lives to God through meaningful acts of penance and worship. The Prophet once said of it, “Hurry to go on your pilgrimage if it is due upon you, for none among you knows what will happen to him tomorrow.” (Ahmad)
For details, see the post:
Emerick, Yahiya. The Meaning of the Holy Qur’an in Today’s English (p. 829). Unknown. Kindle Edition.