Devarim 26:3

אשר יהיה בימים ההם [AND THOU SHALT GO UNTO THE PRIEST] THAT SHALL BE IN THOSE DAYS — These apparently redundant words suggest: you have none else than the priest who lives in your days (you are only concerned with him) (cf. Sifrei Devarim 298:3; Rosh Hashanah 25b; see also Rashi on Deuteronomy 17:9). ואמרת אליו AND SAY UNTO HIM that you are not ungrateful (Sifrei Devarim 299:1). הגדתי היום I PROFESS THIS DAY — [the expression "this day" implies that the declaration is made] one once a year, but not twice a year [even when bringing from a different fruit or crop] (Sifrei Devarim 299:2).

וּבָאתָ֙ אֶל־הַכֹּהֵ֔ן אֲשֶׁ֥ר יִהְיֶ֖ה בַּיָּמִ֣ים הָהֵ֑ם וְאָמַרְתָּ֣ אֵלָ֗יו הִגַּ֤דְתִּי הַיּוֹם֙ לַיהֹוָ֣ה אֱלֹהֶ֔יךָ כִּי־בָ֙אתִי֙ אֶל־הָאָ֔רֶץ אֲשֶׁ֨ר נִשְׁבַּ֧ע יְהֹוָ֛ה לַאֲבֹתֵ֖ינוּ לָ֥תֶת לָֽנוּ׃

And thou shalt go to the priest that shall be in those days, and say to him, I profess this day to the Lord thy God, that I am come to the country which the Lord swore to our fathers to give us.