Devarim 31:29

אחרי מותי כי השחת תשחתון [FOR I KNOW THAT] AFTER MY DEATH YE WILL UTTERLY CORRUPT YOURSELVES — But, you see, as a matter of fact, that all the days of Joshua they did not corrupt themselves, for it states, (Judges 2:7) “And the people served the Lord all the days of Joshua”?! (How, then, could Moses say that they would corrupt themselves after his death, by which he evidently meant immediately after his death, cf. v. 16)? But we may derive from here that one’s pupil should be as dear to him as his own self: — it appeared to Moses that so long as Joshua would live it would be as though he himself would be living (he thus alluded by the words “after my death” to a period after Joshua’s death).

כִּ֣י יָדַ֗עְתִּי אַחֲרֵ֤י מוֹתִי֙ כִּֽי־הַשְׁחֵ֣ת תַּשְׁחִת֔וּן וְסַרְתֶּ֣ם מִן־הַדֶּ֔רֶךְ אֲשֶׁ֥ר צִוִּ֖יתִי אֶתְכֶ֑ם וְקָרָ֨את אֶתְכֶ֤ם הָרָעָה֙ בְּאַחֲרִ֣ית הַיָּמִ֔ים כִּֽי־תַעֲשׂ֤וּ אֶת־הָרַע֙ בְּעֵינֵ֣י יְהֹוָ֔ה לְהַכְעִיס֖וֹ בְּמַעֲשֵׂ֥ה יְדֵיכֶֽם׃

For I know that after my death you will surely become corrupted, and turn aside from the way which I have commanded you; and evil will befall you in the latter days; because you will do evil in the sight of the Lord, to provoke him to anger through the work of your hands.