Revākhaṇḍa ascribed to the Vāyupurāṇa (RKV) 227.27

227.27

ekāśanaṃ brahmacaryaṃ bhūśayyāṃ satyavāditām /
varjanaṃ ca parānnasya pratigrahavivarjanam //

eating once a day, celibacy, sleeping on the ground, speaking the truth,
avoiding food belonging to others, and abstaining from accepting gifts;