Proverbs 13:17
17 A wicked messenger falleth into mischief: but a faithful ambassador is health.
Here we have, 1. The ill consequences of betraying a trust. A wicked messenger, who, being sent to negotiate any business, is false to him that employed him, divulges his counsels, and so defeats his designs, cannot expect to prosper, but will certainly fall into some mischief or other, will be discovered and punished, since nothing is more hateful to God and man than the treachery of those that have a confidence reposed in them. 2. The happy effects of fidelity: An ambassador who faithfully discharges his trust, and serves the interests of those who employ him, is health; he is health to those by whom and for whom he is employed, heals differences that are between them, and preserves a good understanding; he is health to himself, for he secures his own interest. This is applicable to ministers, Christ's messengers and ambassadors; those that are wicked and false to Christ and the souls of men do mischief and fall into mischief, but those that are faithful will find sound words to be healing words to others and themselves.
Proverbs 25:13
13 As the cold of snow in the time of harvest, so is a faithful messenger to them that send him: for he refresheth the soul of his masters.
See here, 1. What ought to be the care of a servant, the meanest that is sent on an errand and entrusted with any business, much more the greatest, the agent and ambassador of a prince; he ought to be faithful to him that sends him, and to see to it that he do not, by mistake or with design, falsify his trust, and that he be in nothing that lies in his power wanting to his master's interest. Those that act as factors, by commission, ought to act as carefully as for themselves. 2. How much this will be the satisfaction of the master; it will refresh his soul as much as ever the cold of snow (which is hot countries they preserve by art all the year round) refreshed the labourers in the harvest, that bore the burden and heat of the day. The more important the affair was, and the more fear of its miscarrying, the more acceptable is the messenger, if he have managed it successfully and well. A faithful minister, Christ's messenger, should be thus acceptable to us (Job xxxiii. 23); however, he will be a sweet savour to God, 2 Cor. ii. 15.
Proverbs 25:19
19 Confidence in an unfaithful man in time of trouble is like a broken tooth, and a foot out of joint.
1. The confidence of an unfaithful man (so some read it) will be like a broken tooth; his policy, his power, his interest, all that which he trusted in to support him in his wickedness, will fail him in time of trouble, Ps. lii. 7. 2. Confidence in an unfaithful man (so we read it), in a man whom we thought trusty and therefore depended on, but who proves otherwise; it proves not only unserviceable, but painful and vexatious, like a broken tooth, or a foot out of joint, which, when we put any stress upon it, not only fails us, but makes us feel from it, especially in time of trouble, when we most expect help from it; it is like a broken reed, Isa. xxxvi. 6. Confidence in a faithful God, in time of trouble, will not prove thus; on him we may rest and in him dwell at ease.