וּבִקַּשְׁתֶּ֥ם מִשָּׁ֛ם אֶת־יְהוָ֥ה אֱלֹהֶ֖יךָ וּמָצָ֑אתָ כִּ֣י תִדְרְשֶׁ֔נּוּ בְּכָל־לְבָבְךָ֖ וּבְכָל־נַפְשֶֽׁךָ׃
Mas si desde allí buscares á SEÑOR tu Dios, lo hallarás, si lo buscares de todo tu corazón y de toda tu alma.
Ibn Ezra
with all your heart explained below [comment on 30: 10]
Sforno
ומצאת, even though you will not have a Temple at your disposal once you are exiled, not any of its sacred vessels.
Or HaChaim
ובקשתם משם….בכל לבבך, "and you will seek (G'd) from there with all your heart, etc. Verses 29 and 30 require analysis. [Basically, the author tries to explain why repentance is mentioned only after exile, and why exile by itself does not appear to be classified as an affliction. Ed.] Remember there are two types of penitence. There is the kind of repentance which is self-induced when people become aware they have sinned and want to rehabilitate themselves to be in good standing with their Creator. The second type of repentance is only the result of the sinner first having suffered severe afflictions at the hands of his enemies, etc. The words: "you will seek from there the Lord your G'd" refer to the people whose repentance was not due to their first having suffered persecution, but was motivated by their fondness of G'd. Moses promises "you will find Him because you seek Him with all your heart" even though you may have committed the most serious sins, such as idolatry, as detailed in verse 28. The fact that you found your way back to G'd will save you from having to experience afflictions.