Thirukkural-On Wealth-Avoidance Of Faults-Kural-436

V V S Iyer would say:

“If the prince correcteth his own faults and then looketh into those of others, where is the ill that can approach him?"

people, who live in glass-houses do not throw stones, because they cannot afford to do so. Wise men, therefore, make it a point to keep themselves free of faults, before they think of correcting the faults of others.

The bible speaks also 'of the need to remove the beam from one"s own eye, before taking note of and proceeding to remove a speck from the other person"s eye".
(Mathew: 7, 35)

it is the basic principle of Inter-personal relationship that the manager, who seeks to know why other people behave as they do, should study himself to understand his own behaviour as a first step. This only will enable him to understand the attitudes and behaviour of other persons in the right perspective and to adopt the right measures to influence their behaviour towards constructive and good channels.