Aap Ki Kasam.

Rajesh Khanna plays Mumtaz's jealous husband who begins to doubt her fidelity when his best friend Sanjeev Kumar enters their lives. She is unable to convince Rajesh Khanna that she loves only him. He leaves her, not knowing that she is pregnant with his child. Depressed and confused, Rajesh Khanna becomes a homeless wanderer, while Mumtaz remarries to provide a secure home for her child. Many years later, the truth dawns on him as he turns up, a broken man, at his own daughter's wedding.