俱舍論記 6.215

6.215

「言前因者至名增上果」者，釋第二句。謂能作因，有增上力。增上之果名增上果，從因立名。

Regarding "Speaking of the first cause ... is called the sovereign fruit": it explains the second line. Meaning that the efficient cause has sovereign power. The fruit of sovereignty is named the sovereign fruit (adhipati-phala), named after the cause.