Did any of the scholars say that a missed prayer is forfeited due to an excuse if it is not made up immediately upon the removal of the excuse and is left for days out of laziness, such that only repentance is obligatory?

None of the scholars have said that the missed prayer falls if it is not made up immediately. Al-Bukhari and Muslim narrated that the Messenger of Allah, peace and blessings be upon him, said: "Whoever sleeps through a prayer or forgets it, let him pray it when he remembers it, for there is no expiation for it except that."

As for the sayings of the scholars regarding making up missed prayers: - The Malikis and Hanbalis: It is obligatory to make it up immediately. The intended immediacy is the customary one, not the absolute one. The Hanbalis qualified immediacy to apply unless it harms one's body or livelihood. - The Shafi'is: If one missed it due to an excuse, making it up is on delay, but immediate make-up is recommended. If it was missed without an excuse, there are two opinions: The more correct view among the Iraqis is the recommendation of immediate make-up and the permissibility of delay. The more correct view among the Khurasanis is the obligation of immediate make-up. - The Hanafis: The correct view among them is the permissibility of making it up immediately or delaying it.