It is a poor heart that never rejoices.
and It is a sad heart that never rejoices.Prov. Even a habitually sad person cannot be sad all the time. (Sometimes used to indicate that a habitually sad person is happy about something.) Jill: I've never seen Sam smile before, but today, at his retirement party, he smiled. Jane: It is a poor heart that never rejoices.
rejoice at something
to celebrate or revel about something. Everyone rejoiced at the lucky events that had saved them. We all rejoiced at the outcome of the election.
rejoice in someone or something
to take great joy at someone or something. I am in love and I rejoice in my beloved! Roger rejoices in a good night's sleep.
rejoice over something
to celebrate because of something. Everyone rejoiced over their good fortune. What happened to us next was nothing to rejoice over.