What is the meaning of the Prophet's (peace and blessings be upon him) saying: "That is ribat, that is ribat, that is ribat"?

The desirable Ribat is to confine oneself to obedience, and it includes performing ablution thoroughly despite difficulties, taking many steps towards the mosques, and awaiting the next prayer after a prayer, as if it is the best type of Ribat or one of the readily available types of Ribat.