זֶה־הַ֭יּוֹם עָשָׂ֣ה יְהוָ֑ה נָגִ֖ילָה וְנִשְׂמְחָ֣ה בֽוֹ׃
Ten to dzień sprawił Bóg, radujmy się i cieszmy nim.
Rashbam
בעבור זה, this was the reason G’d performed miracles for me so that I would subsequently perform this sacrificial service for Him. We find something analogous to this thought in Psalms 118,24 זה היום עשה ה' נגילה ונשמחה בו, “This is the day that the Lord has made, in order for us to exult and rejoice on it.”