Matthew Poole and continuators on 1 Peter 1:6

6 Wherein ye greatly rejoice , though now for a season (if need be ) ye are in heaviness , through manifold temptations .

This refers to the whole foregoing Sentence, ye rejoice in your being kept by the Power of God unto Salvation.

The Greek word signifies something more than a bare Rejoicing, and therefore is added to a word that signifies to rejoice, Matth. 5.12. and implies an outward Expression of the inward Gladness of the Heart, by Looks, Words, Gestures, &c. Some read the word in the Imperative Mood by way of Exhortation, but the Indicative, according to our Translation, seems most agreeable to the Context, in which, as yet, he commends the Saints, to whom he writes, for the Grace of God in them; descending to his Exhortation afterward, v. 13.

Viz. while this life lasts, which is but a little time, 2 Cor. 4.17.

If God see it fit, needful for your good, and conducing to his Glory; intimating, that God doth not always afflict Believers, but when he sees just Cause, and never doth it without cause.

Quest. How could they be in Heaviness, and yet rejoice? Ans. Their Grief and Joy were about different Objects, they might be in Heaviness by reason of present Afflictions, and rejoice in hope of future Glory; they might grieve as Men, and rejoice; as Saints; Sense of Suffering might affect them, and yet the Faith of better things coming, relieve them. If their Heaviness did in any degree abate their Joy, yet it did not wholly hinder it; and tho their Joy did overcome their Heaviness, yet it did not wholly exclude it.

He so calls Afflictions from the end and effect of them, the Trial of their Faith, Luke 22.28. Acts 20.19. Gal. 4.14. Iames 1.2. 2 Pet. 2.9. he calls them manifold, as being not only numerous, but various, and of divers kinds.