הִ֭נֵּה יִסַּ֣רְתָּ רַבִּ֑ים וְיָדַ֖יִם רָפ֣וֹת תְּחַזֵּֽק׃
Behold, thou hast instructed many, And thou hast strengthened the weak hands.
Rashi on Job
Behold, you have chastised many who multiplied words; you admonished them and chastised them.
Malbim on Job
Job's almost instantaneous loss of faith would be a lesson to all. The Providential retraction of his prosperity had revealed that his faith had only ever been instrumental; based not on love of God but on the expectation of His blessings and bounty. Job deserved punishment. Had he remained silent, no-one would have known. But now everyone knew and they would see his punishment as proof that God does govern.
Rashi on Job
and...weak hands of those who feared the retribution that came upon them. You used to strengthen [them] and say, “Fear not, for that is the Divine Standard of Justice.”