All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Tawassul is making something, which has a position and status with Allah, a means for the acceptance of supplication, by asking Allah through it to grant something or to ward off harm, by virtue of the status and rank of the mediator with Allah.
The permissibility of seeking intercession through prophets and righteous individuals is established in Islamic teachings and is not considered shirk or prohibited. Rather, it is recommended by the majority of scholars, and they base this on various evidences, including the following hadith:
Othman Ibn Haneef narrated that a blind man came to the Prophet (PBUH) and said: "Pray to Allah to heal me. The Prophet (PBUH) said: "If you wish, I shall pray for you; and if you wish, I shall delay that for you and that will be better for you." [According to another report, he said: "…Or if you wish, you can be patient and that will be better for you."] He said: Pray for me (now). So he instructed him to do wudoo’ and do it well, then to pray two rak‘ahs and say this du‘aa’ (supplication): "O Allah, I ask You and I turn to You by virtue of Your Prophet Mohammad, the Prophet of mercy. O Mohammad, I turn by virtue of you to my Lord concerning this need of mine, that it might be met for me. O Allah, accept his intercession concerning me and accept my intercession concerning him." So the man did that and he was healed. [Sunan An-Nasa'I, Vol. 9/P.245].
Imam Nawawi (may Allah have mercy on him) mentioned: "It was narrated from Al-Utbi that he said: "I was sitting by the grave of the Prophet (PBUH) when a Bedouin man came and said: "Peace be upon you, O Messenger of Allah! I have heard Allah saying: {If they had only, when they were unjust to themselves, come unto thee and asked God’s forgiveness, and the Apostle had asked forgiveness for them, they would have found God indeed Oft-returning, Most Merciful}. [An-Nisa`/64]. So I have come to you seeking forgiveness for my sins, seeking your intercession with my Lord.' Then he started to recite poetry:
O best of those buried in the earth, the most exalted of them,
The earth and the skies are perfumed by his fragrance
My soul is sacrificed for a grave where you reside,
In it are chastity, generosity, and honor
He then departed, and my eyes followed him, I saw the Prophet (PBUH) in my sleep, and he said to me: "O 'Utbi, catch up with the Bedouin and give him glad tidings that Allah has forgiven him." [Al-Adhkar / p. 206].
Here are texts from scholars of the four Islamic jurisprudential schools regarding the permissibility of seeking intercession through prophets and righteous individuals:
In the Hanafi school, it is stated in [Fath Al-Qadeer by Al-Kamal Ibn Al-Humam (may Allah have mercy on him), Volume 3, page 181]:
"A person can ask Allah, The Most High, for his needs while seeking intercession through the status of His Prophet (PBUH). The greatest and most important matters to ask for are a good ending, contentment, and forgiveness. Then, one can ask the Prophet for intercession, saying, 'O Messenger of Allah, I ask you for intercession. O Messenger of Allah, I ask you for intercession, and I seek nearness to Allah through you, that I may die as a Muslim adhering to your religion and Sunna."
In the Maliki school, Ibn Al-Hajj Al-Maliki (may Allah have mercy on him) stated in his book [Al-Madkhal," Volume 1, page 259]:
"Seeking intercession through the Prophet (PBUH) is a means to relieve burdens of sins and transgressions, because the blessing and greatness of his intercession with his Lord are beyond comparison with any sin. Therefore, let one who visits his grave, during Hajj or Umrah, rejoice, and let one who has not visited him turn to Allah with the intercession of His Prophet (peace and blessings be upon him). O Allah, do not deprive us of his intercession, for he is honored in Your sight. Amen, O Lord of the worlds. Whoever believes otherwise is deprived from the reward. Hasn't he heard the words of Allah The Almighty: If they had only, when they were unjust to themselves, come unto thee and asked God’s forgiveness, and the Apostle had asked forgiveness for them, they would have found God indeed Oft-returning, Most Merciful.' [An-Nisa'/64]…..."
In the Shafi'i school, Imam Al-Nawawi (may Allah have mercy on him) said in his book [Al-Adhkar, page 205] while discussing the etiquettes of visiting the Prophet's grave (PBUH):
"Then one returns to their initial position facing the face of the Messenger of Allah (PBUH), interceding through him to his Lord, exalted and high."
In the Hanbali school, Imam Al-Mardawi (may Allah have mercy on him) said in his book [Al-Insaf Fi Ma'rifat Al-Rajih Min Al-Khilaf volume 2, page 456]: "It is permissible to seek intercession through a righteous person, according to the correct opinion in the school, and some said it is recommended. Imam Ahmad said: "One may seek intercession through the Prophet (peace be upon him) in their supplications, and he affirmed this in the book [Al-Mustaw'ib] and other works……………"
It is worth reminding that the issue of Tawassul is considered among the Zani (Speculative, ambiguous or uncertain) matters of jurisprudence where differences of opinion are permissible. However, we have seen that the majority of scholars from the Sunni schools of thought have stated its permissibility and even its recommendation. Therefore, we find that earlier scholars mentioned this issue in the context of praying for rain (Salat Al-Istisqaa) or visiting the Prophet's grave, and they did not consider it among matters of creed.
Making the issue of Tawassul a matter of creed upon which a person is judged as Kafir or misguided is considered an act of extremism and an entry point for labelling people as Kafir.
The issue is almost unanimously agreed upon, but it falls under subsidiary matters where denial, causing discord, and dispute is not permissible. It is well known that denial is not allowed in Zani jurisprudential matters, let alone accusing someone of Kufr, innovation or misguidance. Moreover, the majority of the scholars agree on the permissibility of Tawassul. And Allah The Almighty Knows Best.
