וּבַשָּׁנָ֣ה הַחֲמִישִׁ֗ת תֹּֽאכְלוּ֙ אֶת־פִּרְי֔וֹ לְהוֹסִ֥יף לָכֶ֖ם תְּבוּאָת֑וֹ אֲנִ֖י יְהוָ֥ה אֱלֹהֵיכֶֽם׃
E no quinto ano podereis comer o seu fruto, para que vos aumente a sua produção; Eu sou Hashem, vosso Deus.
Ibn Ezra
So shall you do even to your maid-servant refers back to “supply him with a bonus” [: 14] (even though it is remote — compare the antecedents of “He must make restitution; if he has nothing wherewith to pay…” [Exodus 22: 2], “if these three…” [Exodus 21: 11], and many others [see also comment on Leviticus 19: 25]), because a woman’s ear is not pierced [Qiddushin 17b].
Bartenura
"Five years [is the age] for [the study of] Scripture": We learn it from orlah (the prohibition to eat fruit from a new tree), as it is written (Leviticus 19:23-25), "three years will they be orlah, etc. And in the fourth year all of its fruit will be holy praises" - that his father should teach him the shape of the letters and recognition of the vowels [in the child's fourth year]. "And in the fifth year you shall eat its fruit; [so that] you will add to your produce" - from here and onward, stuff him like an ox.