We have here a precept, and a reason for it. Both are difficult. The precept is unusual, and the reason ambiguous.
I. The precept is a precept of prudence. It says, There is a great work before you a work which requires workmen. The labourers are few at the best, and they must not be made fewer by wanton self-sacrifices. Think of the work, think of the object, think of souls, think of the Saviour; think of these more than of yourselves. Martyrdom itself may be a sublime selfishness, enthusiasm may exaggerate even sacrifice; or, at least, the sacrifice of the life may be nobler, more heroic, more divine than the sacrifice of the death. Each as God wills; but you must interpret the will of God by the exigencies of the work. Flight may be courage, if it be flight for Christ and with Christ.
II. The work of Christ in the world will never be finished till He comes. Not only will the workmen, one by one, be removed by death the work itself will be cut short, unfinished, by the advent of Christ. "Ye shall not have finished the cities of Israel, till the Son of Man be come." Our Lord thus ministers to our necessities by warning us against several mistakes which are apt to spoil and ruin true work. One of these is the demand beforehand for a roundness and completeness of defined duty, which is not often to be found, and which must certainly not be waited for. The life and work, and the Christ-work of which this text tells, are never finished till the Son of man comes. (1) One reason for this lies in the mere sequence of human generations. Births and deaths are incessant. "One generation goeth, and another generation cometh," but they are both on the stage at once during a large part of the lifetime of earth, and the board is never cleared for a new beginning. (2) Another and a deeper reason lies in the nature of the work. The most real work of all is the intangible, impalpable thing which we call influence. Influence is the thing which Christ looks for, and it is an indefinite, and so an interminable thing. (3) We can see one other reason for this arrangement the incompleteness of all work that is worth the name; and it is the security thus given for the salubriousness of labour.
C. J. Vaughan, Contemporary Pulpit,vol. viii., p. 257.
Reference: Matthew 10:23. H. Ware, Expositor,2nd series, vol. ii., p. 202.