Is gathering in a house for several days for the purpose of fasting, performing Qiyam al-Layl, and reciting the Quran, while taking provisions, considered the legitimate Ribat, and is this act of worship a bid'ah?

This type of work, though permissible in principle, becomes an innovation (bid'ah) if performed in this manner and adopted as a Sunnah. Its inclusion in ribat (frontier-guarding/spiritual devotion) is in the general sense, which is the confinement of the self to obedience, based on the Prophet Muhammad's (peace be upon him) saying: "Shall I not tell you of something by which Allah erases sins and raises ranks?" They said: "Yes, O Messenger of Allah." He said: "Performing ablution thoroughly despite difficulties, taking many steps towards the mosques, and waiting for one prayer after another; that is ribat." As for the specific meaning, which is guarding the frontiers, it is not included in this. It is mentioned in the Hadith: "A day of ribat in the way of Allah is better than the world and all that is in it."