Matsyapurana 54.7

54.7

nakṣatrapuruṣaṃ nāma vrataṃ nārāyaṇātmakam
pādādi kuryādvidhivad viṣṇunāmānukīrtanam //

Lord Śiva said :—Nârada ! You have put a very useful question for the benefit of all. Hear about the vow which is beneficial to widows. There is a religious observance (Vrata) which is known as nakṣatrapuruṣa Vrata, which should be devoutly kept. It (nakṣtrapuruṣa Vrata) is worship of Nârâyaṇa in the figure which should be made according to rule, having feet, etc., and the names of Viṣṇu should be recited.—6-7.