כִּ֣י אִם־יִפֹּ֔לוּ הָאֶחָ֖ד יָקִ֣ים אֶת־חֲבֵר֑וֹ וְאִ֣יל֗וֹ הָֽאֶחָד֙ שֶׁיִּפּ֔וֹל וְאֵ֥ין שֵׁנִ֖י לַהֲקִימֽוֹ׃
Sebab jika mereka jatuh, yang seorang akan mengangkat temannya; tetapi celakalah orang yang seorang diri, yang jatuh dan tidak ada orang kedua untuk mengangkatnya.
Rashi
For if they fall. [To be understood] according to its apparent meaning. And regarding Torah studies, if his studies are too difficult for him, his companion will review them with him, or if he errs and is not exact in what he heard from his teacher, his companion will set him on the truth[ful course].14The Gemara in Maseches Berachos 63b states that Torah scholars who sit alone and engage in Torah study become foolish and will eventually sin [by erring].
Rashi
But woe to him. But woe to him וְאוֹי לוֹ=וְאִי לוֹ.15Rashi renders this interpretation because ואילו is spelled ‘full’, i.e. with a yud. (Sifsei Chachomim)