Mbh 13.58.2a

"'Bhishma said, "A piece of land that is agreeable to the sight, fertile, situate in the midst of delightful scenes adorned with diverse kinds of metals, and inhabited by all sorts of creatures, is regarded as the foremost of sports. A particular portion of such land should be selected for digging a tank. I shall tell thee, in due order, about the different kinds of tanks. I shall also tell thee what the merits also are that attach to the digging of tanks (with the view of drawing water for the benefit of all creatures). The man who causes a tank to be dug becomes entitled to the respect and worship of the three worlds. A tank full of water is as agreeable and beneficial as the house of a friend. It is gratifying to Surya himself. It also contributes to growth to the deities. It is the foremost of all things that lead to fame (with respect to the person who causes it to be excavated). The wise have said that the excavation of a tank contributes to the aggregate of three, Righteousness, Wealth and Pleasure. A tank is said to be properly excavated, if it is made on a piece of land that is inhabited by respectable persons. A tank is said to be subservient to all the four purposes of living creatures. Tanks, again, are regarded as constituting the excellent beauty of a country. The deities and human beings and Gandharvas and Pitris and Uragas and Rakshasas and even immobile beings--all resort to a tank full of water as their refuge. I shall, therefore, tell thee what the merits are that have been said by great Rishis to be attached to tanks, and what the rewards are that are attainable by persons that cause them to be excavated. The wise have said that that man reaps the merit of an Agnihotra sacrifice in whose tank water is held in the season of the rains. The high reward in the world that is reaped by the person who makes a gift of a thousand kine is won by that man in whose tank water is held in the season of autumn.