1 Peter 1:6

Wherein ye greatly rejoice, though now for a little while, if need be, ye have been put to grief in manifold trials,

wherein ... There are several notions in vogue as to what, exactly, is the antecedent; but the most obvious meaning is that the whole "situation" just discussed is being given as the logical reason why they greatly rejoice, or are commanded to greatly rejoice. "The Greek verb might be taken also as an imperative, `Wherefore rejoice'"[17] This is also given as an alternative in RSV margin.

Ye greatly rejoice ... This is a simple statement of fact, rejoicing being mentioned almost continually throughout the New Testament, as when Paul and Silas rejoiced and sang hymns in the night (Acts 16:25).

Though now for a little while ... This is not to be understood as a prophecy that their trials would be of short duration, but relates to the fact of earthly life being almost infinitely shorter than eternal life.

Ye have been put to grief in manifold trials ... The trials coming upon the Christians to whom Peter wrote were more than were normally expected. "Here is a reference to the weight of persecutions being felt by Christians."[18] Later in the letter, Peter will give a number of glimpses of the hatred, vilification, and evil speakings which, even then, were an increasing storm of opposition to the faith.

[17] David H. Wheaton, op. cit., p. 1239.

[18] Stephen W. Paine, Wycliffe New Testament Commentary (Chicago: Moody Press, 1971), p. 970.