Mbh 12.37.2f

[121] As a eunuch is unproductive with women, as a cow is unproductive with a cow, as a bird lives in vain that is featherless, even so is a Brahmana that is without mantras. As grain without kernel, as a well without water, as libations poured on ashes, even so is a gift to a Brahmana void of learning. An unlearned Brahmana is an enemy (to all) and is the destroyer of the food that is presented to the gods and Pitris. A gift made to such a person goes for nothing. He is, therefore, like unto a robber (of other people's wealth). He can never succeed in acquiring regions of bliss hereafter.' I have now told thee in brief, O Yudhishthira, all that was said (by Manu on that occasion). This high discourse should be listened to by all, O bull of Bharata's race."'"