Md. Code, Real Property § 14-105

In the absence of special agreement to the contrary, if a real estate broker employed to sell, buy, lease, or otherwise negotiate an estate, or a mortgage or loan secured by the property, procures in good faith a purchaser, vendor, lessor, lessee, mortgagor, mortgagee, borrower, or lender, as the case may be, and the person procured is accepted by the employer and enters into a valid, binding, and enforceable written contract, in terms acceptable to the employer, of a sale, purchase, lease, mortgage, loan, or other contract, as the case may be, and the contract is accepted by the employer and signed by him, the broker is deemed to have earned the customary or agreed commission. He has earned the commission regardless of whether or not the contract entered into is performed, unless the performance of the contract is prevented, hindered, or delayed by any act of the broker.