Praise be to Allah.
Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him) said: “If someone says, ‘I believe in Allaah, and I put my trust in Allaah, and I rely on Allaah’, there is nothing wrong with that. This is the attitude of every believer – he puts his trust in Allaah, believes in Him and relies on Him.
But with regard to the phrase, ‘and I seek the protection of the Messenger of Allaah (peace and blessings of Allaah be upon him)’, these are reprehensible words. Seeking the protection of the Messenger of Allaah (peace and blessings of Allaah be upon him) after his death is not permissible.
Seeking his protection during his lifetime with regard to matters where he had the ability to do something was permissible. Allaah says (interpretation of the meaning):
“And if anyone of the Mushrikoon (polytheists, idolaters, pagans, disbelievers in the Oneness of Allaah) seeks your protection then grant him protection so that he may hear the Word of Allaah (the Qur’aan)”
But seeking the protection of the Messenger of Allaah (peace and blessings of Allaah be upon him) after his death is major shirk. Anyone who hears someone saying such words should advise him, because he may have heard that from some people and not understand its meaning, but if you tell him and explain to him that this is shirk, Allaah may benefit him at your hands. And Allaah is the Source of strength.