sumatyas tanaya drptah
hayam anvesamanas te
samantan nyakhanan mahim
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
[King Sagara had two wives, Sumati and Kesini.] The sons of Sumati, who were very proud of their prowess and influence, following the order of their father, searched for the lost horse. While doing so, they dug into the earth very extensively.