The question is clarified: why is it written "for this the beloved praised" in singular form, whereas several good deeds that Hashem did for His people Israel were previously mentioned, and it should have said "for these"? 'This' refers to the immediately preceding event: "And the waters covered their enemies; not one of them remained. For this the beloved praised and exalted to G-d"—specifically for this, meaning the downfall of the enemy, and not for the other miracles and wonders mentioned earlier, which pertain to the salvation of Israel, "You redeemed us from Egypt," "You killed all their firstborn and redeemed Your firstborn Israel, etc." They praised only for this, because they are "beloved," and therefore they mentioned only the downfall of the enemy, "And the waters covered their enemies; not one of them remained."