ما رواه محمد بن يعقوب الكليني في كتاب الرسائل عمّن سمّاه قال: كتبت إلى أبي الحسن عليه السّلام أنّ الرجل يحب أن يفضي إلى إمامه ما يحب أن يفضي إلى ربّه، قال: فكتب إن كان لك حاجة فحرّك‏ شفتيك‏ فإنّ‏ الجواب يأتيك‏

Narrated from al-Kulayni in his book "Al-Rasael" from a person,

I wrote to Abi al-Hasan Imam Ali Naqi (ع) that a person wants to have a private/secret conversation with his Imam like how he has a private/secret conversation with his Lord.

Imam (ع) wrote back to him, "If you have any need, then bring your lips into motion, and surely the answer will come to you."

[Source: Kashf al-Mahajjah – Ibn Taoos, Pg. 211]