Is it true that Imaam Ibn Taymiyyah (may Allaah have mercy upon him) was the first to refute the permissibility of Tawassul? Please see the following quote:
Allamah Taqee-ud-Deen Al-Subki (may Allaah have mercy upon him) and other Muhadditheen have stated that Haafiz Ibn-Taymiyyah (may Allaah have mercy upon him) – who passed away in the year 728 Hijri - was the first to refute the permissibility of this form of Tawassul (Shifaa-us-Siqaam pg. 293).

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Know, may Allaah have mercy on you, that Tawaassul (i.e. seeking nearness to Allaah by virtue of someone or something) is of two kinds: permissible and impermissible.

Permissible Tawassul: Is to invoke Allaah by virtue of His Names and Attributes and by virtue of one's good righteous actions, or by requesting a righteous person to supplicate Allaah in your favour. There is no difference of opinion among the scholars that this kind is permissible.

Impermissible Tawassul: It is to invoke Allaah by virtue of Prophets and righteous people, and this is what Ibn Taymiyyah forbade. Whoever claims that Ibn Taymiyyah was the first person to forbid invoking Allaah by virtue of someone or something is wrong. Indeed the companions and the righteous predecessors and their followers forbade the impermissible Tawassul (second type) and absolutely no one is reported to have permitted it, though they were earnest in endeavouring in righteous actions and used to supplicate Allaah much and humble themselves to Him. If this type was permissible they would have invoked Allaah by virtue of the Prophet after his death as they used to supplication by his virtue in his lifetime. In fact, they supplicated by virtue of Al-'Abbaas when they were severely affected by drought in the presence of Al-Muhaajireen and Al-Ansaar . (This was after the Prophet's death). 'Umar said: 'O Allaah, we used to supplicate You for rain by virtue of our Prophet and You gave us rain, and now we are supplicating You by virtue of the uncle of the Prophet (i.e. by him supplicating for us to receive rain) so accept our supplication.' [Al-Bukhari] All the companions approved of this type of supplication and none of them refuted it. Mu'aawiyah Ibn Abu Sufian supplicated for rain in the same manner when he was a caliphate. Were the invocation by virtue of the Prophet after his death permissible, the companions would not have abandoned it and made a supplication by Al-'Abbaas or others in their lifetime. What has been reported, though, regarding the permissibility of supplicating by virtue of pious people or by virtue of the Prophets, may Allaah exalt their mention, after their death is either weak or fabricated. Among those who forbade this type of Tawassul is Imaam Abu Haneefah and the scholars of his School and they said: 'One should not invoke Allaah by virtue of any human being and no one should say: 'O Allaah, I am asking You by virtue of Your Prophets.' Many scholars of Abu Haneefah's School stated this opinion. Abu Yoosuf said: 'Abu Haneefah said: 'No one should ask Allaah except by virtue of His Names and Attributes, and I dislike (i.e. deem it prohibited) for people to say 'by virtue of Your creature.' This is also the opinion of Abu Yoosuf as he said: 'I dislike anyone to say 'by virtue of so and so, or 'by virtue of Your Prophets and Messengers', or 'by virtue of Al-Haram mosque or Al-Mash'ar Al-Haram (i.e. Al-Muzdalifah, a well-known place near Makkah where pilgrims have to stop and stay for the whole night of the 10^th of Thul-Hijjah)'.

Al-Qaddoori said: 'It is not permissible to ask Allaah by virtue of a creature because creatures have no right on the Creator.' This is the view of Al-Kaasaani, Az-Zayla'i, Ibn Al-Hammam and the noble scholar Ibn 'Abdul-Wahaab. Shaykh Ibn Taymiyyah said: 'Abu Haneefah and the scholars of his School said that supplicating by virtue of Prophets, may Allaah exalt their mention is forbidden. Imaam Maalik has not stated anything contradicting this meaning so whoever reports about him, that he has permitted this type of Tawassul has no evidence, or that the scholars of his School had said so, or indeed, any other Muslim Imaam other than Maalik, like Ash-Shaafi'ee, Ahmad, and others.' Whoever, said they permitted this type of Tawassul has indeed lied about them. Even if some scholars said that it is lawful (to supplicate by virtue of others), it is confirmed that many amongst them forbade it, so it is a matter upon which they differed, and it has to be balanced against the Word of Allaah and the Sunnah of His Prophet like in any other question on which there are differences. Allaah says (which means): {And in whatsoever you differ, the decision thereof is with Allaah (He is the ruling Judge).}[42:10]. The Prophet said: "Those of you who will live after me will see a great disagreement. Thus you must adhere to my Sunnah and the way of the rightly-guided Caliphs. Hold to it and stick tight to it." [Ahmad and Abu Daawood]

Shaykh Al-Islam Ibn Taymiyyah stated evidences from the Book of Allaah and the Sunnah of the Prophet about the prohibition of the second type of Tawassul, so whoever wants to refer to them should consult Majmoo' Al-Fataawi.

Allaah knows best.