from the Extended Mahāvaṁsa V 331-338
Athekadivasaṁ Rājā Catusambuddhadassinaṁ
kappāyukaṁ Mahākāḷaṁ Nāgarājaṁ mahiddhikaṁ
suṇitvāna tam-ānetuṁ hemasaṅkhalibandhanaṁ.
One day, King (Asoka), having heard about the Nāga King Mahākāla, of great power, who had lived for an aeon and seen the Four Perfectly Awakened Ones, had him brought into his presence bound by golden chains.
Pesayitvā tam-ānetvā setacchattassa heṭṭhato
pallaṅkamhi nisīdetvā, nānāpupphehi pūjiya,
After sending for and bringing him, and having him sit under the white canopy on the throne, he worshipped him with many flowers, and surrounded him with sixty thousand (dancing) women, and said:
“Saddhammacakkavattissa Sabbaññussa Mahesino
rūpaṁ anantañāṇassa dassehi mama Bho.” iti
“Show me the form of the one who set rolling the True Dhamma, the Omniscient Great Sage with endless knowledge, Dear.”
nimmāsi Nāgarājā so Buddharūpaṁ manoharaṁ.
The King of the Nāgas created a captivating form of the Buddha, endowed with the thirty-two marks, the eighty characteristics, encircled by a fathom-wide light, adorned with the garland of rays.
Taṁ disvā ‘tipasādassa viṁhayassa ca pūrito
“Etena nimmitaṁ rūpaṁ īdisaṁ! Kīdisaṁ nu kho
Tathāgatassa rūpan?”-ti Āsi pītunnatunnato.
Having seen that, full of faith and astonishment, (Asoka said): “Such is this (mere) created form! What would (have been) the Realised One’s (true) form?” And his joy was raised on high.
Akkhipūjan-ti saññātaṁ taṁ sattāhaṁ nirantaraṁ,
mahāmahaṁ Mahārāja kārāpesi mahiddhiko.
For seven days he uninterruptedly (performed) what is known as the Eye-Worship, and the Great King, of great power, had a great festival celebrated.
The Eye-Worship means he paid respect by looking at the form uninterruptedly for seven days; a similar thing is said in the later texts about the Buddha after he attained Awakening: he spent the second week doing unblinking worship (animisapūja) to the Bodhi Tree (see e.g. Jinacarita v. 277).