Is it permissible to enter into ihram for Umrah from Jeddah for someone coming from Najran after attending a wedding ceremony, or is it obligatory to enter into ihram from Yalamlam? And if it is not permissible, is it permissible to wear the ihram garments from Najran and travel by plane?

If you intend to perform 'Umrah after attending the wedding in Jeddah, you must enter into the state of ihram from the miqat or when you are parallel to it in the airplane. This is based on the Prophet's (peace and blessings be upon him) saying: "These miqats are for them (the people of those places), and for those who come by them from other than their people, among those who intend Hajj and 'Umrah." However, if you are hesitant, you are not required to enter into ihram at the miqat, and you may pass the miqat without ihram. Then, you can enter into ihram from Jeddah if you decide to perform 'Umrah. Wearing the ihram garments from Najran is permissible, but the actual ihram begins when you intend to enter into the rituals and avoid the prohibitions.