What is the legal evidence relied upon by Imam Abu Hanifa regarding the permissibility and validity of the marriage of an adult, sane woman without the condition of a guardian's presence?

Scholars have differed regarding the validity of marriage without a guardian (wali). Some, like Abu Hanifa, Zufar, Al-Sha'bi, and Al-Zuhri, asserted its validity. They based their argument on the Almighty's saying: "There is no blame upon you for what they do with themselves in a lawful manner," and the hadith: "The previously married woman has more right to herself than her guardian." However, the majority of scholars stipulate the guardian's presence for the validity of the marriage contract.