Where plaintiffs were employed as brokers to sell a contract for the sale of real estate at a profit of $1,000 net to their clients, and they produced a purchaser ready, able and willing to take the contract on the terms prescribed, but defendant refused to assign the same, and sold it to another, plaintiffs performed their obligations and were entitled to recover commissions. Levy v. Trimble, 94 N. Y. S. 3, 47 Misc. 394.