Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Volume 11, Page 217, Question 5 of Fatwa No.1734
Question: During Hajj, we see some people (males) cutting short their hair just from the bottom and around their heads only leaving the rest of the head untouched. They don’t cut any of the hair from there. When we told them that cutting the hair should be done equally all over the head, they said that this is what is required. So, which of the two actions is obligatory?
Response: That which is obligatory is for the head to either be shaved or hair cut equally from all over the head during Hajj and ‘Umrah. It is not required to take from every single hair. That which has been mentioned [in the question] is not sufficient according to the correct opinions of the People of Knowledge and nor is it from the Sunnah of Muhammed (sal-Allaahu ‘alayhi wa sallam).
And with Allaah lies all success and may Allaah send prayers and salutations upon our Prophet (sal-Allaahu ‘alayhi wa sallam) and his family and his companions.