John Gill Commentary Deuteronomy 4:30

"When thou art in tribulation, and all these things are come upon thee, in the latter days thou shalt return to Jehovah thy God, and hearken unto his voice:" — Deuteronomy 4:30 (ASV)

When you are in tribulation
In a strange land, in the power of a foreign enemy, and used ill:

and all these things are come upon you ;
captivity, thraldom, hard labour, and want of the necessaries of life:

[even] in the latter days :
in their present captivity for the rejection of the Messiah:

if you turn to the Lord your God ;
as the Jews will when they are converted and brought to a sense of their sin, and of their need of Christ, and seek to him as their Saviour, as they will do in the latter day, (Hosea 3:5) (2 Corinthians 3:16)

and shall be obedient unto his voice ;
not of the law only, but of the Gospel also, proclaiming peace, pardon, righteousness, and salvation by him whom they have pierced.