Imād al-Dīn Abū Jafar Muhammad ben Alī ben hamza al-tūsī known as Ibn hamza al-tūsī was theTwelver Shia scholar of fiqh in 5th/11th and 6th/12th centuries who wrote the book al-Wasila. He is also famous as "Sahib al-Wasila" for writing this book. Ibn Hamza should be regarded a follower of Al-Shaykh al-Tusi's school. A comparison between his rulings inal-Wasila and al-Shaykh al-Tusi's rulings shows that he has accepted the principles of al-Shaykh al-Tusi's fiqh.
Ibn Hamza should be considered among the followers of al-Shaykh al-Tusi's school. A comparison between his rulings in al-Wasilaand al-Shaykh al-Tusi's rulings shows that he has accepted the principles of al-Shaykh al-Tusi's fiqh. He can also be regarded among fiqh scholars who have been considered as restating al-Shaykh al-Tusi's fiqh and his followers by Humsi (the fiqh scholar of the second half of 6th/12th century). However, it should be noted that Ibn Hamza not only has stood against some opinions of al-Shaykh al-Tusi and perhaps sometimes has wanted to moderate his ruling, but he has also discussed new minor issues in fiqh which have not been discussed in al-Shaykh al-Tusi's books.

One of the most distinguished characteristics of Ibn Hamza's fiqh should be considered his approach in stating the rulings. He first determines different possibilities of the issue in general with number and then discusses each of them in details. In his divisions, he has differentiated between obligatory andrecommended, forbidden and disliked, performing and abandoning, quality and quantity and has mentioned each separately. In the introduction to al-Wasila, he says that this categorization makes remembrance of rulings easy. Although, Ibn Hamza cannot be considered the inventor of this method, but he perfected it. His definition of jurisprudential terminology at the beginning of some chapters is another characteristic of his fiqh. Beside al-Shaykh al-Tusi, he benefited from the opinions of other contemporary scholars in fiqh as well; for example, in some cases, he openly has mentioned the opinions of Sallar al-Daylami. He was also influenced from Ibn Barraj to some extent.