HOW DID THE LORD BUDDHA DWELL?
Bhikkhus, Mindfulness with Breathing (Anapanasati) that one has developed and make much of has great fruit and great benefit.
Even I myself, before awakening, when not yet enlightened, while still a Bodhisatva (Buddha to be), lived in this dwelling (way of life) for the most part. When I lived mainly in this dwelling, the body was not stressed, the eyes were not strained, and my mind was released from the asava (corruptions, cankers) through non-attachment.
For this reason, should anyone wish "may my body be not stressed, may my eyes be not strained, may my mind be released from the asava through non-attachment," then that person ought to attend carefully in his heart to this Mindfulness with Breathing meditation.
(Samyutta Nikaya. Samyutta LIV, Sutta 8)