Please help me ?? ii) Is the contract between Marshall and Ted valid? discuss?

Marshall went to nearby florist to buy to his wife Lily’s a favorite flower ,He took a bouquet of Lilies, and pays the florist. The florist, Ted however didn’t have the exact change for Marshall. Therefore, Ted said to Marshall that he don’t have to pay for the Lilies, provided that Marshall are to pray for Ted’s unhealthy wife, Zoey for a month. After a short thinking, Marshall then agreed and left the store with the flowers