The 62-year-old is currently working with his former club Esteghlal as a board member.
Last year, Ferguson praised Hejazi, who trained with Manchester United for a month and appeared in a reserve match against Stoke City after the 1978 World Cup, and expressed his best wishes for him.
In a letter dated April 14, 2010, Ferguson wrote that he had only recently learned about Hejazi’s illness.
“I was sorry to hear that you have not been feeling too well. I just thought I would drop you a line on behalf of the players and staff, as I wanted you to know that we are all thinking about you. On a personal note, I would like to thank you for your loyal support and devotion to the club over the years, which is very much appreciated,” Ferguson wrote.
“I know that the last few months have been difficult for you but trust that you will gain some comfort knowing that you are in our thoughts and prayers,” he added.
Hejazi played for Iran’s national team 62 times from 1968 to 1980.
On Tuesday, he published the following reply to Ferguson on his personal website:
Dear Sir Alex Ferguson,
Something has always puzzled me all my life. Why is it that when I am in special need of help, the kind gesture usually comes from unexpected corners?
I received your letter expressing kindness in a language which the deaf can hear and the blind can see. Being in your thoughts and prayers comforts me and keeps me going. I thank you from the bottom of my heart, the heart that has no bottom.
For the concern you have shown, I have no other words but to say thank you very much.