Shaykh al-Islām Ibn Taymiyyah (رحمه الله) said:[1]
For we, after acquaintance with what the Messenger (صلى الله عليه وسلم) came with, know by necessity that he did not legislate for his ummah that they call upon anyone from the dead, neither the prophets, nor the righteous or others besides them, neither with the word istighāthah (seeking rescue) and nor with other than it, and nor with the word istiʾādhah (seeking refuge) or other than it. Just like he did not legislate for his ummah that they prostrate to a dead person or other than a dead person and what is similar to this. Rather, we know that he prohibited from all these matters and that it is from the shirk which Allāh and His Messenger made unlawful. However, due to the preponderance of ignorance, and scant knowledge of the remnants of the messengership amongst many of the latecomers, takfīr is not made of them on account (of what has been mentioned) until that which the Messenger (صلى الله عليه وسلم) came with becomes clear to them (yatabayyan) from that which opposes it. For this reason, never did I explain this issue to anyone who understood the foundation of Islām, ever, except that he grasped it and said, "This (establishment of the proof) is the [very] foundation of the religion," and one of the senior amongst the knowledgeable shaykhs from our associates said, "This is the greatest of what you have explained to us" due to his knowledge that this is the foundation of the religion."
Arabic Text: