Hebrews 13:1

Love being the fountain and foundation of all moral duties, our apostle begins with it, and places it at the head of all the rest, as comprehending our whole duty towards our neighbour.

Note here, The duty commanded is love; the special duty recommended is brotherly love, or that brotherly affection which every true Christian chiefly bears to all his fellow members in Christ for grace's sake; and the manner of the injunction or command is, that his brotherly affection do continue and constantly abide, not in the pretence and appearance of it only, but in the truth and reality of it, for there are innumerable occasions which will be ready to impair and weaken it, if it be not well grounded; alas, unsuitableness of natural temper, differences in judgment, and matters of opinion, inconsistent worldly interest, readiness to provocation, or to be provoked, pride on the one hand, or envy on the other, will sadly occasion the temporary decay, yea, at last the total loss of this noble grace, if it be not well grounded and deeply rooted.

Learn hence, That brotherly love is very apt to impair and decay, if we endeavour not continually its preservation and revival. Lord, how marvellous is it, that so many amongst us can persuade themselves that they are Christians, and yet be not only is the power and glory of Christianity will run very low, yea, the concerns of religion will more and more run to ruin.