ויאמר ה' אל משה אמור אל הכהנים. ובמדרש רבתי (סכ"ו סי' ד') זהו שאמר הכתוב (תהילים י״ט:ג׳) יום ליום יביע אומר, שמעתי ממורי יום ליום יביע אומר ולילה ללילה יחוה דעת, כי אמרו חכמינו ז"ל (סנהדרין ד"ז ע"א) תחילת דינו של אדם עבור ביטול תורה שנאמר (משלי י"ז י"ד) פוטר מים ראשית מדון וכו', אפס שסובר שיוכל לפטור מהדין עבור טרדת פרנסה ביום, ובלילה שובת מטרדתו, אך דיום החורף מכריעו וכו' וליל הקיץ סותר וכו' וז"ש וכו' ודפח"ח:
(בן פורת יוסף בסופו דקכ"ז ע"ג). And the L-rd said to Moses: Speak to the priests… (Leviticus 21:1)
This is what the verse says: “Day to day utters speech” (Psalms 19:3)1From the Midrash on this verse (Vayikra Rabbah 26:4).
I heard from my Master [a commentary on the verse]: “Day to day utters speech, and night to night expresses knowledge.” The Sages have said, “A person is judged first2In the World to Come. for the time he wasted from Torah study, as it says: ‘The beginning of strife is [like] the release of water’ (Proverbs 17:14).”3Sanhedrin 7a. The simple meaning of this verse is that strife and contentiousness break forth like a gush of water. Water is a classic metaphor for Torah, as in the verse: “Ho, every one that thirsts, come you for water…” (Isaiah 55:1). However, the Talmud interprets this verse different: “The beginning of strife” – that is, the beginning of a person’s judgment is over “the release of water” – the time he wasted from studying Torah.
Does a person really believe that he can escape judgment due to the burden of making a living by day, and the [need to] rest from his work at night? The days of winter contradict this, and the nights of summer destroy [his argument].4In the past, most people would work only until nightfall. The short winter days prove that a person can finish work early and still make a living, thus contradicting the argument that a person must work long hours, leaving himself no time for Torah study. Likewise, the short nights of summer demonstrate that a person can make do with less sleep and still function. Why, then, should he need so much sleep the rest of the year, rather than study Torah?
The connection of this teaching to the verse from Psalm 19 may be that day and night express words that negate a person’s arguments. Alternatively, the Midrash that cites this verse (Vayikra Rabbah 26:4), speaks of the day and night as “borrowing” from each other throughout the year. The long summer days borrow hours from the night, and the long summer nights borrow hours from the day. Only on the spring and autumn equinoxes are day and night equal. This is in order to prove to people that there is always time to study Torah.
Ben Poras Yosef, p. 127c