Surah 49. Al-Hujurat, Ayah 4

While this relates in the first instance to the Prophet, it may also be taken to apply to any supreme leader of the community (amir al-mu'minin) who acts as the Prophet's successor (khalifah) and rules in his name, i.e., under the aegis of Islamic Law. (As regards the Prophet himself, the above exhortation to reverent behaviour implies, in the view of many outstanding Islamic thinkers, a prohibition to "call out to him" when visiting his tomb.)

 A group from the tribe of Bani Tamîm came to see the Prophet (ﷺ) while he was taking a nap in the afternoon. They stood outside the homes of his wives and started calling him out loud.

To shout aloud to your Leader from outside his Apartments shows disrespect both for his person, his time, and his engagements. Only ignorant fools would be guilty of such unseemly behaviour. It is more seemly for them to wait and bide their time until he is free to come out and attend to them. But, with the Messenger of Allah, much is forgiven that is due to lack of knowledge and understanding. In an earthly Court, ignorance of the Law excuseth no man. If a man behaved in that way to the General of an army or the Governor of a Province, not to speak of an earthly King, he would be laid hands on by the Guard, and could never gain the access he desires.