Rashi: When we have a Yom Tov, we do not engage in obscene talk and frivolity [like all nations].

Radak: Hashem says, I will choose a time for Yisrael to leave Galus.

Rashi: We put to our hearts to praise You according to the event of the day.

Radak: I will judge their enemies with straightness.

Malbim: The verse depicts that straightness is the foundation on which the world stands. It is as if the world stands on pillars, and they are established on one base - straightness. A Midrash ¹ says that the world stands on one pillar, called Tzadik. If that base (straightness) would slip, automatically the land would melt and all its inhabitants would perish (verse 4).