The film Muqaddar Ka Sikandar (1978) starred Amitabh Bachchan, Vinod Khanna, Raakhi, Rekha, and Amjad Khan, had music by Kalyanji-Anandji, and lyrics by Anjaan. Each song in the film was memorable, but if I had to pick one, it would be my all-time favorite Amitabh song, O Saathi Re.
The song begins about three minutes into the video, and the essence of the little talk at the outset is that the speaker (Sikandar) is being praised and rewarded for a charitable contribution to orphans. After noting that had he known he would be praised in public, that he wouldn't be at the event, he suggests that he hasn't done anyone a favor, since he spent his life as an orphan. And in all his loneliness, it is this song that he cherishes and trusts for cheer when most needed. It is a song that he was introduced to by a companion (who she is, is anyone's guess). Here it is then:
Here are the lyrics and my translation: