SB 9.9.11

rathena vāyu-vegena
 prayāntam anudhāvatī
deśān punantī nirdagdhān
 āsiñcat sagarātmajān
Synonyms: 
rathena — on a chariot; vāyu-vegena — driving at the speed of the wind; prayāntam — Mahārāja Bhagīratha, who was going in front; anudhāvatī — running after; deśān — all the countries; punantī — sanctifying; nirdagdhān — who had been burnt to ashes; āsiñcat — sprinkled over; sagara-ātmajān — the sons of Sagara.
Translation: 
Bhagīratha mounted a swift chariot and drove before mother Ganges, who followed him, purifying many countries, until they reached the ashes of Bhagīratha’s forefathers, the sons of Sagara, who were thus sprinkled with water from the Ganges.