A short reminder I found on fridaynasiha.com…
It is the duty of a Muslim to help fellow Muslims to stay on the straight path. The Prophet (peace and blessings be upon him) enumerated the conditions to be met in the task of advising others: “Each one of you is like a mirror to the other.” (Tirmidhi) In another hadith the Prophet said: “Every Muslim serves as another Muslim’s mirror. He safeguards his rights in his absence as well.” (Abu Dawud) The following norms emerge in light of the above ahadith:
1. One should not look for the lapses and weaknesses of others. For a mirror does not seek defects. Only on coming face to face does a mirror reflect you.
2. One should not be criticised in one’s absence. Once again the similitude of the mirror should be kept in mind; it does not reflect someone in absentia.
3. One should not exceed limits in criticising someone else. For a mirror does not magnify or diminish any feature.
4. Criticism should be forthright and free of any ulterior motive. For, once again, a mirror does not entertain any revenge or grudge.
5. One’s criticism should be made with sincerity, genuine concern, pain and love. This removes any bitterness caused by criticism. Sincerity in this context signifies one’s concern for the ultimate accountability in the Hereafter. One should help a fellow Muslim in order to avoid any punishment for him on the Day of Judgement. Nor should one entertain any superiority complex. Humility and not arrogance makes mutual care and advice effective.
“Inter Personal Relations” – Khurram Murad, pp. 34, 35