'Him I sang praises to, therefore art thou my only one,' thus said Kaushîtaki to his son. 'Do thou revolve his rays, then thou wilt have many sons.' So much in reference to the Devas.

In plain words: The sage Kaushitaki told his son that he had worshipped only the sun itself, and that is why he had only one son. He told his son to meditate on the sun's many rays as well, so he would be blessed with many sons.