Positive commandment · Mitzvat Aseh #119 of 613
For the produce of the fourth year to be sacred
להיות נטע רבעי קודש
The verse · Vayikra 19:24
וּבַשָּׁנָה הָרְבִיעִת יִהְיֶה כׇּל־פִּרְיוֹ קֹדֶשׁ הִלּוּלִים לַה׳
“But in the fourth year all its fruit shall be holy for praisegiving to the Lord.”
The Rambam’s words
For the produce of the fourth year to be sacred, as [Leviticus 19:24] states: "Its produce shall be sacred, [an object of] praise to G-d...."
להיות נטע רבעי קודש, שנאמר: "יִהְיֶה כָּל פִּרְיוֹ קֹדֶשׁ הִלּוּלִים" (ויקרא יט, כד).
Why · Sefer HaChinuch #247
Fourth-year plant
“It is from the roots of the commandment that G-d wanted man to be inspired to praise G-d, blessed be He, with the beginning of the best fruits of his trees; so that the pleasantness of G-d, may He be blessed, and His blessing rest upon him, and [that] his fruits be blessed.”
Who & when
“And this commandment is practiced at the time of the [Temple] in the Land by males and females, but not outside the Land.”
Where in the Mishneh Torah
Hilchot Second Tithes and Fourth Year's Fruit הלכות מעשר שני ונטע רבעי