Tantra Sāra 1.015
चतुर्विशन्मूर्तयोSस्याः कथिता वर्णदेवताः। तद्भेदः पौरुषं सूक्तं वेदाः पुरुषसूक्तगाः ॥१५॥
The twenty four forms of the lord manifest from the 24 syllables(of Gayatri). From it manifests Purusha Sūkta. Then Vēdas manifest from Purusha Sūkta.
24 forms of the lord:
From Vāsudēva comes Kēshava, Nārāyana, Mādhava, Vāsudēva, Purushottama, and Janārdhana;
From Sankarshana comes Gōvinda, Vishnu, Madhusūdhana, Sankarshana, Adhōkshaja and Upēndra;
From Pradyumna comes Trivikrama, Vāmana, Shrīdhara, Pradyumna, Narasimha and Hari;
From Aniruddha comes Hrishīkēsha, Padmanābha, Dāmōdara, Aniruddha, Achyuta and Krishna;
The Purusha Sūkta has three Pādas: 1-5, 6-10, 11-16.
They manifest from the three Pādas of Gāyatri respectively.
oṁ bhūrbhuvaḥ svaḥ = Vyahritis
tatsaviturvarēṇyaṁ = Pādas 1 (1-5) of Purusha Sūkta = Rig;
bhargō dēvasya dhīmahi = Pādas 2 (6-10) of Purusha Sūkta = Yajur;
dhiyō yō naḥ pracōdayāt = Pādas 3 (11-16) of Purusha Sūkta = Sama;
A pictorial representation: