CC Madhya 12.215

yata piye tata tṛṣṇā bāḍhe nirantara
mukhāmbuja chāḍi’ netra nā yāya antara
Word for word: 
yata — as much; piye — they drink; tata — so much; tṛṣṇā — thirst; bādhe — increases; nirantara — incessantly; mukha-ambuja — the lotuslike face; chāḍi’ — giving up; netra — the eyes; — do not; yāya — go; antara — separate.
Translation: 
As their eyes began to drink the nectarean honey of His lotus face, their thirst increased. Thus their eyes did not leave Him.
Purport: 

In the Laghu-bhāgavatāmṛta (1.5.538), Śrīla Rūpa Gosvāmī has described the beauty of the Lord in this way:

asamānordhva-mādhurya-taraṅgāmṛta-vāridhiḥ
jaṅgama-sthāvarollāsi-
rūpo gopendra-nandanaḥ

“The beauty of the son of Mahārāja Nanda is incomparable. Nothing is higher than His beauty, and nothing can equal it. His beauty is like waves in an ocean of nectar. This beauty is attractive both for moving and for nonmoving objects.”

Similarly, in the tantra-śāstra there is another description of the Lord’s beauty:

kandarpa-koṭy-arbuda-rūpa-śobha-
nīrājya-pādābja-nakhāñcalasya
kutrāpy adṛṣṭa-śruta-ramya-kānter
dhyānaṁ paraṁ nanda-sutasya vakṣye

“I shall relate the supreme meditation upon Lord Śrī Kṛṣṇa, the son of Nanda Mahārāja. The tips of the toes of His lotus feet reflect the beauty of the bodies of unlimited millions of Cupids, and His bodily luster has never been seen or heard of anywhere.”

One may also consult Śrīmad-Bhāgavatam (10.29.14) in this connection.