It sounds more like a tip than a gift. Your husband performed a service for Mrs Someone and received a payment from her because of that service.
"Section 102 of the tax code instructs us that “Gross income does not include the value of property acquired by gift, bequest, devise or inheritance.” It helpfully clarifies that this exception to the income tax does not apply to “any amount transferred by or for an employer to, or for the benefit of, an employee.”
When you tip a waitress, she's not suddenly your employee. But the tip is still income, not a gift from you to the waitress. The tip is considered a "transfer for the benefit of an employee" from the quote in my previous reply.
ahj3939 t1_j2f56bj wrote
Unless it's included on their W2 or 1099 I would treat it as a gift.
Also when you say "gave us" a check if that is accurate and you are not an employee it further enforces this is a gift and not wages/bonus.