Valmiki Ramayana Ayodhya Kanda Sarga 110 Shloka 24
Original Shlokaस राजा सगरो नाम य: समुद्रमखानयत्। इष्ट्वा पर्वणि वेगेन त्रासयन इमाः प्रजाः।।2.110.24।
1 source checked for this shloka
सः he, सगरो नाम राजा a king, Sagara by name, यः who, इष्ट्वा having performed a sacrifice, पर्वणि on a fullmoon day, वेगेन swiftly, इमाः प्रजाः these men, त्रासयन्तम् frightening, समुद्रम् the ocean, अखानयत् excavated.
The king Sagara performed a sacrifice on the fullmoon day. And swiftly dug the ocean that frightened the people.