Aisha lived a very long time and taught her nephew Qasim ibn Muhammad ibn Abu Bakr. Many Hadith are quoted through Qasim.
Al-Qāsim ibn Muhammad ibn Abu Bakr was one of the seven most famous jurists in Medina, and was considered as the most knowledgeable among them. He was highly influential in disseminating early traditions of hadith, fiqh (jurisprudence) and tafsir (exegesis) of the Qur'an.
He was a pious imam and was very knowledgeable in the narration of the Traditions. Abu Zannad said, "I never saw anyone better than him in following the Sunnah of the Prophet (s). In our time no one is considered perfect until he is perfect in following the Sunnah of the Prophet and Qasim is one of the perfected men."
He learned hadith and fiqh from his aunt and from Ibn Abbas. He was a transmitter of hadith and criticised the use of a hadith if its text was put before the Quran and established Sunnah.
He left and went to al-Qudayd, a place between Makkah and Madinah on the 9th of Muharram, where he died. The year was 108 (or 109) AH/730 or 731 CE, and he was seventy years old.
Abdu r-Rahman ibn Abi Zannad said that his father mentioned, "I did not see anyone who knew the Sunnah better than al-Qasim."
According to the 11th-century Hilyat al-Awliya: "He was able to extract the deepest juristic rulings and he was supreme in manners and ethics."
Imam Malik narrated that Umar ibn Abd al-Aziz, considered the sixth rightly-guided caliph (after Abu Bakr, Umar, Uthman, Ali and Hasan) said, "If it were in my hands, I would have made al-Qasim the caliph in my time."
Sufyan said, "Some people came to al-Qasim with charity which he distributed. After he distributed it, he went to pray. While he was praying, the people began to speak negatively about him. His son said to them, "You are speaking behind the back of a man who distributed your charity and did not take one dirham from it for himself." Quickly his father scolded him saying, Do not speak, but keep quiet." He wanted to teach his son not to defend him, as his only desire was to please God. He had no concern for the opinion of people.
Yahya ibn Sayyid said, "We never found, in our time in Madinah, anyone better than al-Qasim." Ayyub as-Saqityani said, "I have not seen anyone better than Imam Qasim. He left 100,000 dinars behind for the poor when he passed away, and it was all from his lawful earnings."
His student, Abu'z-Zinad 'Abdullah ibn Dhakwan said about him:
"I never saw a faqih with more knowledge than al-Qasim. I never saw anyone who had more knowledge of the Sunna than him."