By Swami Harshananda
Sins and their expiation is one of the important subjects dealt with in the smṛtis and dharmaśāstras. Apart from paścāttāpa which is a prerequisite, many modes are described for getting rid of or for lessening the effects of sins. One such mode is of japa or the muttering of some Vedic mantras.
The Manusmṛti mentions that by the japa of the Kautsa (sukta), even a drinker of surā or wine becomes pure. The eight mantras of Ṛgveda attributed to the sage Kautsa are known as the Kautsasukta. The sage Kautsa is said to have prayed to Agni for freeing him from the sin of killing a woman.
He had killed a demoness called Dirghajihvi at the instance of Indra, since she was troubling the sages engaged in the performance of sacrifices. All the eight ṛks of this sukta end with the words "ap nah śośucadagham" which means ‘May our sin depart from us!’
- The Concise Encyclopedia of Hinduism, Swami Harshananda, Ram Krishna Math, Bangalore