Shatapatha Brahmana 4.5.8.14

4.5.8.14

tadāhuḥ | na sahasre 'dhi kiṃ cana dadyātsahasreṇa hyeva sarvān kāmānāpnotīti tadu hovācāsuriḥ kāmameva dadyātsahasreṇāha sarvān kāmānāpnoti kāmeno asyetaraddattam bhavatīti

Now they say, one ought not to give anything above a thousand (cows), because by a thousand he obtains all the objects of his desire. But Âsuri said, 'Let him give according to his wish: by a thousand he indeed obtains all his wishes; and anything else (that he gives) is likewise given at his wish.'