What should a son do regarding his father's invitation to come to Saudi Arabia and work there for a lower salary, knowing that the father did not raise him? Would his disobedience displease God?

Obeying a parent's command to travel to them is not obligatory if it harms the child. The child is not considered disobedient for refusing in such a case, due to the Prophet's (PBUH) saying: "There should be neither harming nor reciprocating harm." However, one must continuously show kindness and do good to them within one's capacity, for that is among the best acts of drawing closer to Allah.