Cutting some of one’s hair in Hajj or ‘Umrah
Question

                A man cut his hair on one side after doing ‘Umrah, then he went back to his family, and found out that what he had done was not correct. What should he do?
Praise be to Allah. 
          This question was put to Shaykh Muhammad 
          ibn ‘Uthaymeen (may Allaah have mercy on him) and he said: 
 
          If he did that out of ignorance, then 
          he should take off his regular clothing (and put on ihraam) and shave 
          his head completely or cut his hair, and what he did will be forgiven 
          because he was ignorant. Shaving or cutting the hair does not have to 
          be done in Makkah; it may be done in Makkah or elsewhere. 
 
          But if what he did was based on a fatwa 
          from one of the scholars, then he does not have to do anything, because 
          Allaah says: 
 
          “So ask of those who know the Scripture, 
          if you know not”
 
          [al-Nahl 16:43]
 
          and some of the scholars think that cutting 
          hair  from part of the head is like cutting hair from all of the 
          head.