Hoyt & Roberts, comps. Hoyts New Cyclopedia of Practical Quotations. 1922.
Gratia, quæ tarda est, ingrata est: gratia namque Cum fieri properat, gratia grata magis. A favor tardily bestowed is no favor; for a favor quickly granted is a more agreeable favor. AusoniusEpigrams. LXXXII. 1.
Nam quamblibet sæpe obligati, si quid unum neges, hoc solum meminerunt, quod negatum est. For however often a man may receive an obligation from you, if you refuse a request, all former favors are effaced by this one denial. Pliny the YoungerEpistles. III. 4.