כִּ֛י י֥וֹם נָקָ֖ם בְּלִבִּ֑י וּשְׁנַ֥ת גְּאוּלַ֖י בָּֽאָה׃
「因為報仇的日子在我心中，救贖我子民的年份已經來到。」
Ibn Ezra
For the day of vengeance, etc. For I will wreak vengeance against my enemies, and I will redeem my friends. גאולי My redeemed. It is participle passive plural with the suffix, first person, referring to God.
Tze'enah Ure'enah
“For I had planned a day of vengeance and My year of redemption arrived” [63:4]. I have had a day in My heart on which to take vengeance and the year of redemption has come.