Dear James,

the praṇava-based meditation on the īśvara that as described in Pātañjala Yogaśāstra (PYŚ) 1.27 and 1.28 (and, of course, its commentaries) is a comparatively early testimony for the practice of meditative visualisation of a "teacher" (see PY 1.26)  in a non-Buddhist source. In this connection the PYŚ cites the follwing stanza that also occurs in the Viṣṇupurāna:

svādhyāyād yogam āsīta yogāt svādhyāyam āmanet |

svādhyāyayogasaṃpattyā para ātmā prakāśate || (PYŚ I.28,5 f. = VPurāṇa 6.6.2)

See on this topic

G. Oberhammer, “Meditation on Mystik im Yoga des Patañjali”, WZKSO 9 (1965) 98-118.

Id., Strukturen yogischer Meditation. Untersuchungen zur Spiritualität des Yoga. Wien 1977 (Österreichische Akademie der Wissenschaften, philosophisch-historische Klasse, Sitzungsberichte, 322 = Veröffentlichungen der Kommission für

Sprachen und Kulturen Südasiens, 132).

Ph. Maas, “The So-called Yoga of Suppression in the Pātañjala Yogaśāstra”, in: Eli Franco (ed.) in collaboration with Dagmar Eigner, Yogic Perception, Meditation, and Altered States of Consciousness. Vienna: Verlag der Österreichischen Akademie der Wissenschaften, 2009 (Sitzungsberichte der phil.-hist. Klasse, 794 = Beiträge zur Kultur- und Geistesgeschichte Asiens, 64), p. 263-282.

With best regards,

Philipp