But though I am not for confession to men in a popish sense, yet I think in three cases there ought to be confession to men:
(1) Firstly, where a person has fallen into scandalous sin and by it has been an occasion of offense to some and of falling to others, then he ought to make a solemn and open acknowledgement of his sin so that his repentance may be as visible as his scandal (2Cor. 2.6-7).
(2) Secondly, where a man has confessed his sin to God, and yet his conscience is still burdened and he can have no ease in his mind, then it is requisite that he should confess his sins to some prudent, pious friend, who may advise him and speak a word in due season (James 5. 16). It is a sinful modesty in Christians that they are not more free with their ministers and other spiritual friends in unburdening themselves and opening the sores and troubles of their souls to them. If there is a thorn sticking in the conscience, it is good to make use of those who may help to pluck it out.
(3) Thirdly, where any man has slandered another and by clipping his good name has made it less influential, he is bound to make confession. The scorpion carries its poison in its tail; the slanderer carried it in his tongue. His words pierce deep like the quills of the porcupine. The person who has murdered another in his good name or, by bearing false witness, has damaged him in his estate, and ought to confess his sin and ask forgiveness: “If you bring your gift to the altar, and there remember that your brother has anything against you; go your way; first be reconciled to your brother, and then come and offer your gift” (Matt. 5.23-24). How can this reconciliation be effected except by confessing the injury? Till this is done, God will accept none of your services. Do not think the holiness of the altar will privilege you; your praying and hearing are in vain till you have appeased your brother’s anger by confessing your fault to him.
Thomas Watson, True Repentence, p.19-20