1 Timothy 6:14

that thou keep the commandment, without spot, without reproach, until the appearing of our Lord Jesus Christ:

The commandment ... As Lenski said:

Some think the word is called "commandment" because the gospel commands men to repent; but the New Testament shows clearly that the gospel itself is called the commandment because its preaching, teaching and inculcation were enjoined upon the apostles (Matthew 28:20ff).[25]

Without spot, without reproach ... Hervey noted that some commentators are uncertain whether these terms should be applied to Timothy's conduct or to the gospel; but they are true either way. The view here is that they are a reference to the kind of life Timothy was enjoined to live in his preaching of the gospel.

The appearing of our Lord Jesus Christ ... This is a reference to the Second Advent of our Lord, all Christian endeavor being carried forward with constant respect to this eventual Coming. There is nothing here to the effect that Paul expected it to occur in his lifetime.