1)
What will fill your mouth with laughter?
1.
Rashi: Hashem will return to have mercy on you.
2.
Malbim: You will receive good in place of the evil that you had until then.
2)
Why did he add "u'Sfasecha Seru'ah"?
1.
Devar Eliyahu (22): Filling your mouth with laughter is hidden. Your lips will be openly full of shouting.
