These words contain a warning, a comforting assurance and a solemn charge. Note:
I. The warning. We must remember that the word "you" is not used here in the sense of our common language that is, to express a single person. Our Lord does not say that Satan had desired to have Peter only, but all the Apostles. The hour was coming, when their faith was to be severely tried, when they were to be sifted as wheat, to see what in them was good corn, and what chaff. In our lives also the words can never be otherwise than true.
II. The comforting assurance. "I have prayed for thee that thy faith fail not." This is spoken of Peter particularly; it is "I have prayed for thee" not, I have prayed for you, but though these words speak of Peter only, yet we have the assurance elsewhere that it is true of us also. Nay, on that very evening when He thus declared that He had prayed for Peter, we know that He prayed for the other Apostles too, and not for them only, but for us also.
III. All are warned of the coming danger; but one is especially prayed for, that being converted himself he might also strengthen his brethren. These words were addressed to Peter, and if we read the first twelve Chapter s of the Acts, we shall find their fulfilment. There we find him, indeed, strengthening his brethren, passing through all quarters, and by signs and wonders, by the word of wisdom, by fervent boldness and love unfeigned convincing the unbelievers, opening the eyes of the ignorant, baffling the threats of the enemy enlightening, cheering, and comforting his fellow-Christians. But this also was said, not to Peter only, but to us. In every society, there are those like him to whom it may be said, "When thou art converted, strengthen thy brethren." There are, and always must be, some who have more influence than their neighbours. Every advantage which we have over others makes us subject to this charge. If we are older, we should strengthen those that are younger; if we have the ascendency given by strength and activity, by decision of character, or by general ability, or by consideration of whatever sort, then we, being converted, should strengthen our brethren; we are answerable not for our souls only, but also in a certain measure, for those of others.
T. Arnold, Sermons,vol. iii., p. 114.
References: Luke 22:31; Luke 22:32. Homiletic Magazine,vol. viii., p. 126; vol. x., p. 133; Preacher's Monthly,vol. i., p. 352.Luke 22:31-34. J. Oswald Dykes, Sermons,p. 263.