Secret counsels are only (inspired) by the Evil One, in order that he may cause grief to the Believers; but he cannot harm them in the least, except as Allah permits; and on Allah let the Believers put their trust. Al-Mujadila 58:10 ⧉
Tafsir:
As a rule, secret whispering is an undesirable action. However, sometimes for some good reason, secret whispering has to be resorted to. In this case, the decisive factor is intention. If it is done with good intentions, it is legitimate but if it is done with evil intentions, it is sinful.