1 Corinthians 13:9

For we know in part, and we prophesy in part;

'For' -explains the reason why these spiritual gifts will cease. All the spiritual gifts had some relationship to the revelation of the Word of God. Gifts such as prophesy and knowledge revealed truth. Gifts such as tongues, healing, and miracles confirmed the divine origin of what was revealed. (Hebrews 2:3; Acts 2:22)

'know in part' -due to the fact that all truth (John 16:13) had not yet been revealed and or recorded. Hence the logical next step.

'we prophesy in part' -the gifts such as prophesy (speaking by divine inspiration) enabled the First Century churches to function, serve God and teach others, and edify it's own members, despite the fact that they didn't possess. N.T., or all the N.T. books. On the one hand they had the OT (Acts 17:11; Romans 15:4), and whatever letters had been written to them or received from other congregations. (Colossians 4:16; 1 Thessalonians 5:27) On the other hand, whatever "gaps" in their knowledge existed, the spiritual gifts filled in, giving revelation as needed. (1 Corinthians 14:30)

Point to Note:

Know in part and prophesy in part both refer to knowledge of the will of God. The context is dealing with "revelation". Keep this in mind as we approach the next verse.

In addition: The spiritual gifts were "limited" in how much revelation they gave. (a) All revelation wasn't given to one prophet. (b) The gifts only gave. "part" of God's revelation at. time. (See Acts 10:1) (c) No prophet or even Apostle ever revealed the whole of God's truth at once. (d) The possession of. single copy of the N.T., was more valuable than any spiritual gift.