Why Talhah (may Allah be pleased with him) was called "Talhah the Generous"

It is narrated from Sayyiduna Musa bin Talhah (may Allah be pleased with him) that Sayyiduna Talhah (may Allah be pleased with him) slaughtered a camel and dug a well on the day of Dhu Qarad, then fed the people and gave them water to drink. So the Prophet (peace and blessings be upon him) said: "O Talhah! You are indeed al-Fayyad (the abundantly generous one)." Thus his name became well known as "Talhah al-Fayyad".
The chain of this hadith is sahih (authentic), but the two Shaykhs did not record it.

Sayyiduna Musa bin Talhah narrates from his father, Sayyiduna Talhah bin Ubaydullah (may Allah be pleased with him), who said: The Messenger of Allah (peace and blessings be upon him) named me "Talhah al-Khayr" (Talhah of goodness) on the day of the Battle of Uhud, "al-Fayyad" (the overflowing in generosity) in the Battle of al-Ushayrah, and "Talhah al-Jud" (Talhah of munificence) on the day of Hunayn.
Mention of the virtues of Muhammad bin Talhah bin Ubaydullah al-Sajjad (may Allah be pleased with him):
Muhammad bin Talhah was among the ascetics who strove to the utmost in worship. The Companions of the Messenger of Allah (peace and blessings be upon him) used to seek blessing through his person and his supplication, and he was the first person to be given the title "al-Sajjad" (the one who prostrates much) because of the abundance of his prostrations.