Canto 3 -
Araṇya-kāṇḍa
Chapter 49: Rāvaṇa Kidnaps Sītā
Text 3.49.8-9

स परिव्राजकच्छद्म महाकायो विहाय तत्।
प्रतिपद्य स्वकं रूपं रावणो राक्षसाधिपः॥

संरक्तनयनः क्रोधाज्जीमूतनिचयप्रभः।
रक्ताम्बरधरस्तस्थौ स्त्रीरत्नं प्रेक्ष्य मैथिलीम्॥

sa parivrājaka-cchadma mahā-kāyo vihāya tat
pratipadya svakaṁ rūpaṁ rāvaṇo rākṣasādhipaḥ

saṁrakta-nayanaḥ krodhāj jīmūta-nicaya-prabhaḥ
raktāmbaradharas tasthau strī-ratnaṁ prekṣya maithilīm

saḥ = the; parivrājaka-chadma = who had disguised himself as a sannyāsī; mahā-kāyaḥ = large-bodied; vihāya = gave up; tat = that form; pratipadya = and returned; svakam = to his original; rūpam = form; rāvaṇaḥ = Rāvaṇa; rākṣasa-adhipaḥ = ruler of the rākṣasas; saṁrakta-nayanaḥ = his eyes were red; krodhāt = due to anger; jīmūta-nicaya-prabhaḥ = and his complexion was that of a cloud; rakta-ambaradharaḥ = he was attired in red garments; tasthau =  standing thus; strī-ratnam = the jewel among women; prekṣya = he looked; maithilīm = at Maithilī.

Rāvaṇa, the large-bodied ruler of the rākṣasas who had disguised himself as a sannyāsī, gave up that form and returned to his original form. His eyes were red due to anger and his complexion was that of a cloud. He was attired in red garments. Standing thus, he looked at Maithilī, the jewel among women.

It is implied that Rāvaṇa hoped that Sītā will accept him upon seeing him in this form.