Charles Ellicott Commentary Isaiah 25:9

"And it shall be said in that day, Lo, this is our God; we have waited for him, and he will save us: this is Jehovah; we have waited for him, we will be glad and rejoice in his salvation." — Isaiah 25:9 (ASV)

It shall be said in that day. —The speakers are obviously the company of the redeemed, the citizens of the new Jerusalem. The litanies of supplication are changed into anthems of praise for the great salvation that has been accomplished for them.