What is the meaning of the Hadith: "He who relies on his wealth becomes poor, he who relies on his intellect goes astray, and he who relies on Allah will not go astray"? Does this mean not using intellect in Ijtihad? And when is intellect used in Ijtihad?

The hadith: "He who relies on his wealth will be poor, he who relies on his intellect will go astray, and he who relies on Allah will never go astray" was not reported from the Prophet, peace and blessings be upon him. Rather, it is attributed to Ali ibn Abi Talib, may Allah be pleased with him.

Intellect holds great importance in Islam for several reasons, including: 1. It is a condition for legal accountability (taklif shar'i). 2. It is one of the five essential necessities (al-ḍarūrāt al-khams) that the Shari'ah came to preserve. 3. It helps in the correct understanding of verses and hadiths, and leads to the comprehension of divine proofs and evidences. The Quran condemned those who do not use their intellect, as in His Almighty saying: (And they will say, "If only we had listened or reasoned, we would not be among the companions of the Blaze").

There is nothing in Islam that contradicts sound intellect; rather, intellect aligns with the Shari'ah. Indeed, those who made their intellect the judge over the texts of the Shari'ah without following the methodology of the Salaf have gone astray. Shaykh al-Islam Ibn Taymiyyah said: "And that does not contradict sound intellect; for whatever contradicts sound intellect is false, and there is nothing false in the Book, the Sunnah, or the Ijma'."