In Tamil version Kamba Ramayanam by Kambar, it is said during war, one day on the verge of Ravana's defeat, Rama gave chance to Ravana, to go today and come tomorrow for fight.
Does this appear in Valmiki Ramaya? If yes, can you quote me the verse
Yes, something similar is mentioned in Valmiki Ramayana: Yuddha Kanda: Sarga 59
प्रयाहि जानामि रणार्दितस्त्वं |
प्रविश्य रात्रिंचरराज लङ्काम् |
अश्वस्य निर्याहि रथी च धन्वी |
तदा बलम् प्रेक्ष्यसि मे रथस्थः || ६-५९-१४३
"O, King of the Ranger of night! I know you have been tormented in the battle. Go and return to Lanka. Having regained your breath, come back in your chariot with your bow and then standing in your chariot, you will witness once more my prowess."