Gen 2:16–17: "in the day that you eat of it, you will surely die"

Says The permission is מִכֹּל עֵץ־הַגָּן אָכֹל תֹּאכֵל, an infinitive absolute with the verb; the warning, בְּיוֹם אֲכָלְךָ מִמֶּנּוּ מוֹת תָּמוּת, "in the day you eat of it you shall surely die," has the same form (BDB "die"). Both address the man in the singular; in 2:17 the LXX has plurals, θανάτῳ ἀποθανεῖσθε. Solomon warns Shimei in the same construction: 1 Kgs 2:37, בְּיוֹם צֵאתְךָ … מוֹת תָּמוּת.

Implies The death threatened here is carried out in 3:19 (כִּי־עָפָר אַתָּה וְאֶל־עָפָר תָּשׁוּב) and 5:5 (וַיָּמֹת), as the Romans 5 note reads it (note.language.Rom.5.12-Rom.5.14.gen-2-3-adam).

Uncertain How "in the day" works. (1) "When": the form means "as soon as you eat," as בְּיוֹם עֲשׂוֹת in 2:4 and 1 Kgs 2:37 show; on that day the man becomes liable, and death follows. Objection: the sentence is not executed that day. (2) Death begins that day as alienation from God (3:8–10, 23–24), with bodily death following; held in the Reformed confession (WCF 6.2, by reference). Objection: the warning names dying, not separation. (3) The sentence is mitigated or deferred in mercy (3:15, 21). Objection: Gen 3 does not say so. No lean is taken among these. An early reading took the "day" as a thousand years (Ps 90:4), so that Adam died within it (see note.historical.Gen.2.1-Gen.2.25.early-christian-readings); it is noted as early, not offered as a live option.

Uncertain Whether bodily death would have come without the trespass is not settled in Gen 2 alone; see Rom 5:12 and 1 Cor 15:21.