Response: I’tikaaf is sunnah (recommended) and righteousness to parents is obligatory, and a recommended act does not override an obligation. It does not contradict the obligation in anyway because the obligation takes precedence over it. Allaah the most High said in a hadeeth qudsee: “My servant does not come closer to Me with something more beloved to Me than that which I have obligated upon him.” So, if your father orders you not to do i’tikaaf, and mentions reasons that mean you do not do i’tikaaf due to his need of you during that time, then the father is the one to weigh that up not you. This is because the scale you have may be unjust and inaccurate. This is because you desire to do i’tikaaf, so you do not consider these excuses as justifiable whereas your father considers them justifiable. So what I advise you is not to make i’tikaaf. Yes, if your father said not to make i’tikaaf without mentioning any just reason for that, you would not be obliged to obey him in this case, as you are not obliged to follow him in a matter which in disobeying him would not cause any harm to him and in obeying him would cause disadvantage to you.
Shaykh Ibn ‘Uthaymeen
Fataawa Ramadhaan – Volume 2, Page 878, Fatwa No.866;
Fataawa ash-Shaykh Muhammad as-Saalih al-‘Uthaymeen – Volume 1, Pages 551-552.fatwaonline.com