Positive commandment · Mitzvat Aseh #125 of 613
To bring the first fruits to G-d's chosen house, [the Temple,]
להביא ביכורים לבית הבחירה
The verse · Shemot 23:19
רֵאשִׁית בִּכּוּרֵי אַדְמָתְךָ תָּבִיא בֵּית ה׳ אֱלֹהֶיךָ לֹא־תְבַשֵּׁל גְּדִי בַּחֲלֵב אִמּוֹ
“The first of the firstfruits of thy land thou shalt bring to the house of the Lord thy God. Thou shalt not boil a kid in its mother’s milk.”
The Rambam’s words
To bring the first fruits to G-d's chosen house, [the Temple,], as [Exodus 23:19] states: "The first fruits of your land...."
להביא ביכורים לבית הבחירה, שנאמר: "רֵאשִׁית בִּכּוּרֵי אַדְמָתְךָ" (שמות כג, יט) (שמות לד, כו).
Why · Sefer HaChinuch #91
Bringing the first-fruits
“It is from the roots of the commandment [that it is] in order to put the word of G-d, may He be blessed, “at the top of our joy,” and that we remember and we know that it is from Him, blessed be He, that all of the blessings of the world come to us.”
Who & when
“And [it] is practiced at the time of the Temple by males with fruits of the Land of Israel and of Syria and of Transjordan, but not with fruits from outside of the Land.”
Where in the Mishneh Torah
Hilchot First Fruits and other Gifts to Priests Outside the Sanctuary הלכות ביכורים ושאר מתנות כהונה שבגבולין