The ending of the letter can be divided as follow:
16:1–4
The collection for the poor in Jerusalem will be mentioned with more details in 2 Cor 8–9 (see Rom 15:26). Here, however, we have interesting information about the custom of collection money on Sunday - probably during liturgical celebrations. The churches in Galatia are mentioned as a point of reference. So, Paul was collecting the money for the poor in Jerusalem in all of the churches he has established (see Gal 2:10).
16:5–9
Paul’s planned trip: First to Macedonia to get the collection from there (see 2 Cor 8:1; 9:1–5) and then to spend some time in Corinth. For certain reasons this plan was aborted (2 Cor 1:15–17).
From 16:8 we know that Paul wrote 1 Cor from Ephesus (Acts 19:8–20:1).
16:10–11 Timothy (see 1 Cor 4:17)
16:12 Apollos (Acts 18:24–27). Was Paul trying to convince Apollos to go with Timothy? Paul says that Apollos did not accept the offer. In Acts 18:27 - Apollos asks for letters, so he could go to Corinth (Achaia - is a province; Corinth was its capital).
16:13–14
This is the last call in this letter related to moral aspect of Christian life. It contains four verbs in imperative: (1) watchfulness - perhaps in reference to (Acts 20:29–31) and/or in reference to Christ’s coming (Mark 13:35); (2) standing in faith; (3) “play the man” - act manly (see 1:12 - stop all those divisions); (4) be strong. Finally, as the last is mentioned love - which Paul discussed in chapter 13. It is a good summary for all churches.
16:15–18
Three brothers are mentioned: Stephanas (see 1 Cor 1:16) - the first baptized by Paul - the firstfruit of Achaia. He is set as an example of service. Probably, there was a house church in his house and he must have been one among the leaders in the church in Corinth.
Stephanus had recently visited Paul in Ephesus with the two other Corinthian brothers - Fortunatus and Achaicus. They may have carried the questions Paul answered in this letter as well as information about conditions in the church.
16:19–21
The Corinthians are greeted by:
“A holy kiss” - (1 Thess 5:26; Rom 16:16; 2 Cor 13:12)
16:22
Why did Paul add this shocking phrase is unclear. It is an excommunication that excludes anyone who does not love the Lord from the community. However, it is interesting that Paul here uses the verb “phileo - love as friendship” (see John 21:15–17). Together with Titus 3:15, this is the only time that Paul uses the verb phileo instead of agapeo for love.
From excommunication Paul moves to the famous prayer of the first Christians - Maranatha - Come Lord Jesus (see Rev 22:20).
16:23–24
The usual ending in verse 16:23 - the grace of Christ. The word “grace” captures the essence of the Gospel. Everything that God has done for us in Christ and through Christ is grace.
However, 16:24 surprises. Instead of love of God (see 2 Cor 13:13), Paul speaks about his love (agapeo) in Christ for them. It seems that Paul wanted to assure of his own love for all the believers in Corinth. That love would be soon tested by the news from Corinth to be brought by Timothy.