Talmud for Pirkei Avot 4:18
רַבִּי שִׁמְעוֹן בֶּן אֶלְעָזָר אוֹמֵר, אַל תְּרַצֶּה אֶת חֲבֵרְךָ בִשְׁעַת כַּעֲסוֹ, וְאַל תְּנַחֲמֶנּוּ בְּשָׁעָה שֶׁמֵּתוֹ מֻטָּל לְפָנָיו, וְאַל תִּשְׁאַל לוֹ בִשְׁעַת נִדְרוֹ, וְאַל תִּשְׁתַּדֵּל לִרְאוֹתוֹ בִשְׁעַת קַלְקָלָתוֹ:
R. Shimon ben Elazar says: Do not appease your friend in the time of his wrath, [as it is written (Exodus 33:14): "My face shall go and I shall put you at ease," the Holy One telling Moses: "Wait until My face of wrath shall pass."], and do not console him while his dead one is lying before him. [For at the time of the destruction (of Jerusalem), the Holy One Blessed be He was, as it were, in mourning; and when the ministering angels tried to console Him, the Holy Spirit said to them: "Do not hasten to console Me."], and do not seek ["openings" to absolve him of his vow] at the time of his vow. [For then, for every opening that you find for him he will say: "Yes, it was with this understanding that I vowed," and you will no longer be able to find an opening for him. And we find that when the Holy One Blessed be He swore to Moses that he would not enter the land, he did not implore Him immediately, but he waited and then he began to implore Him.], and do not try to see him at the time of his undoing [by sin. For then he is ashamed of all men. As we find with Adam — when he sinned, the Holy One Blessed be He did not appear to them (Adam and Eve) until they made girdles, as it is written (Genesis 3:7): "And they made themselves girdles," after which it is written (Ibid 8): "And they heard the voice of the L rd G-d."]
Avot D'Rabbi Natan
He would also say: One who studies Torah in his youth, what is he like? Like a calf which was tamed when it was still small, as it says (Hosea 10:11), “Ephraim became a trained calf, but still wanted to thresh.” One who studies Torah in his old age is like a cow that was never trained until it was too old, as it says (Hosea 4:16), “Israel turned away like a stubborn cow.”
He would also say: One who studies Torah in his youth is like a woman who kneads dough when it is hot. One who studies Torah in his old age, what is he like? Like a woman who kneads dough when it is cold.