וְעָשִׂ֜יתָ חַ֤ג שָׁבֻעוֹת֙ לַיהוָ֣ה אֱלֹהֶ֔יךָ מִסַּ֛ת נִדְבַ֥ת יָדְךָ֖ אֲשֶׁ֣ר תִּתֵּ֑ן כַּאֲשֶׁ֥ר יְבָרֶכְךָ֖ יְהוָ֥ה אֱלֹהֶֽיךָ׃
E celebrarás a festa das Semanas para Yehovah, teu Elohim, da oferta voluntária da tua mão, que deres conforme Yehovah, teu Elohim, te abençoar.
Rashi
מסת נדבת ידך means sufficient (די) free-will offerings of thy hand (i.e. of thy possession) (cf. Targum on Deuteronomy 15:8, which renders די מחסרו by כמסת חסרונה); everything must be in accordance with the blessing which God has bestowed upon you (אשר יברכך): offer peace-offerings of rejoicing and invite guests for the meal.
Chizkuni
ועשית חג שבועות, “you will keep the festival of weeks;” the author refers to his commentary on the significance of this festival in Leviticus chapter 23, where he explained why the Torah did not give us a date for when this festival is to be observed, as opposed to all the other festivals where the month and days they are to be observed have been spelled out.
Ibn Ezra
The letter samekh in the word tribute [Hebrew: missat] is vocalized with a dagesh to indicate the absorption of a nun ; the word comes from “flag” [Hebrew: nes], in the sense of “raising up one’s arm”,