Aphrahat, Demonstration 18:4-5

And concerning virginity and [qaddishutha] I will persuade you that even in that nation [Israel] they [virginity and qaddishutha] were more loved before God and even among that earlier people it [qaddishutha] was better than a great number of births that bring no success. Moses, the man, the great prophet, leader of all Israel, from the time that his Lord spoke to him he loved qaddushutha and he served the Holy One. And he abstained from the world and from procreating and he remained by himself in order to please his Lord.....for if he had performed the duties of marriage he would not have been able perform the greater duties of his Lord. [For] Israel was not able to receive the holy text and the living words that the Holy One spoke to Moses on the mountain until he had [qaddshe] the people for three days. And only then the Holy One spoke to them. ...

If the people of Israel, with whom God spoke only one hour [de-hada sha’ah balhud], were unable to hear the voice of God until [Israel] had [etqaddash] itself three days, even though [Israel] did not go up the mountain and did not go into the heavy cloud; how then could Moses, the man, the prophet, the enlightened eye of all the people, who stood all the time before God, and spoke with him mouth to mouth [min pum apum], How was it possible that he be living in the married state? And if with Israel, that had [etqaddash] itself for only three days, God spoke, how much better and desirable are those who all their days are [meqaddashin], alert, prepared and standing before God. Should not God all the more love them and his spirit dwell among them?

I write you my beloved concerning virginity and holiness [qaddishutha] because I have heard from a Jewish man who insulted one of the brothers, members of our congregation, by saying to him: You are impure [tame’in] you who do not marry women; but we are holy [qaddishin] and better, [we] who procreate and increase progeny in the world.