Verses with the word assuredly in the Old Testament (7 verses):

1 Samuel 28:1
And it came to pass in those days, that the Philistines gathered their armies together for warfare, to fight with Israel. And Achish said unto David, Know thou assuredly, that thou shalt go out with me to battle, thou and thy men.

1 Kings 1:13
Go and get thee in unto king David, and say unto him, Didst not thou, my lord, O king, swear unto thine handmaid, saying, Assuredly Solomon thy son shall reign after me, and he shall sit upon my throne? why then doth Adonijah reign?

1 Kings 1:17
And she said unto him, My lord, thou swarest by the LORD thy God unto thine handmaid, saying, Assuredly Solomon thy son shall reign after me, and he shall sit upon my throne.

1 Kings 1:30
Even as I sware unto thee by the LORD God of Israel, saying, Assuredly Solomon thy son shall reign after me, and he shall sit upon my throne in my stead; even so will I certainly do this day.

Jeremiah 32:41
Yea, I will rejoice over them to do them good, and I will plant them in this land assuredly with my whole heart and with my whole soul.

Jeremiah 38:17
Then said Jeremiah unto Zedekiah, Thus saith the LORD, the God of hosts, the God of Israel; If thou wilt assuredly go forth unto the king of Babylon's princes, then thy soul shall live, and this city shall not be burned with fire; and thou shalt live, and thine house:

Jeremiah 49:12
For thus saith the LORD; Behold, they whose judgment was not to drink of the cup have assuredly drunken; and art thou he that shall altogether go unpunished? thou shalt not go unpunished, but thou shalt surely drink of it.