Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Volume 11, Page 211, Question 3 of Fatwa No.7890
Question: Some people say that if the Day of ‘Arafah (9 Dhul-Hijjah) falls on a Friday, then it is as if someone has performed 7 Hajjs (i.e. he is rewarded as having done so). Is there any evidence from the Sunnah regarding this?
Response: There is no authentic evidence regarding this. [However], some people [also] believe this equates to [having performed] 70 Hajjs or 72 Hajjs, and this is also incorrect.
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.