SB 9.14.42
gandharvan upadhavemams
tubhyam dasyanti mam iti
tasya samstuvatas tusta
agni-sthalim dadur nrpa
urvasim manyamanas tam
so ’budhyata caran vane
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Urvasi said: “My dear King, seek shelter of the Gandharvas, for they will be able to deliver me to you again.” In accordance with these words, the King satisfied the Gandharvas by prayers, and the Gandharvas, being pleased with him, gave him an Agnisthali girl who looked exactly like Urvasi. Thinking that the girl was Urvasi, the King began walking with her in the forest, but later he could understand that she was not Urvasi but Agnisthali.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Srila Visvanatha Cakravarti Thakura remarks that Pururava was very lusty. Immediately after getting the Agnisthali girl, he wanted to have sex with her, but during sexual intercourse he could understand that the girl was Agnisthali, not Urvasi. This indicates that every man attached to a particular woman knows the particular characteristics of that woman during sex life. Thus Pururava understood during sexual intercourse that the Agnisthali girl was not Urvasi.