Srimad-Bhagavatam: Canto 4 - Chapter 1 - Verse 31

Sanskrit:

सदसस्पतय ऊचु:नरदेवेह भवतो नाघं तावन् मनाक्स्थितम् ।अस्त्येकं प्राक्तनमघं यदिहेद‍ृक् त्वमप्रज: ॥ ३१ ॥

ITRANS:

sadasas-pataya ūcuḥnara-deveha bhavatonāghaṁ tāvan manāk sthitamasty ekaṁ prāktanam aghaṁyad ihedṛk tvam aprajaḥ

Translation:

The head priests said: O King, in this life we do not find any sinful activity, even within your mind, so you are not in the least offensive. But we can see that in your previous life you performed sinful activities due to which, in spite of your having all qualifications, you have no son.

Purport:

The purpose of marrying is to beget a son, because a son is necessary to deliver his father and forefathers from any hellish conditional life in which they may be. Cāṇakya Paṇḍita therefore says, putra-hīnaṁ gṛhaṁ śūnyam: without a son, married life is simply abominable. King Aṅga was a very pious king in this life, but because of his previous sinful activity he could not get a son. It is concluded, therefore, that if a person does not get a son it is due to his past sinful life.