Taking zakah from wheat and barley

Musa bin Talhah narrates: We have with us the document of Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that was from the Prophet (peace and blessings be upon him), in which it is mentioned that he (peace and blessings be upon him) collected zakah only from wheat, barley, raisins and dates.
All the narrators of this hadith have been used as evidence, but the two Shaykhs did not record it; and Musa bin Talhah is a senior Tabi'i, whose having lived in the time of Sayyiduna Mu'adh is not disputed.

It is narrated from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "On land watered by rain, natural moisture or floodwater, a tenth ('ushr) is due, and on land watered from wells or by labour, half a tenth (a twentieth) is due." This zakah applies only to dates, wheat and grains; as for cucumbers, melons, pomegranates and green fodder (qadb), the Messenger of Allah (peace and blessings be upon him) has exempted them (that is, no zakah is due on them).
This hadith has a sahih chain, but the two Shaykhs did not record it; and it has a supporting narration (shahid) with a sahih chain:

It is narrated from Sayyiduna Abu Musa al-Ash'ari and Sayyiduna Mu'adh bin Jabal (may Allah be pleased with them both) that when the Messenger of Allah (peace and blessings be upon him) sent the two of them to Yemen to teach the people their religion, he said: "Take zakah only from these four things: barley, wheat, raisins and dates."

Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) said: "No zakah is due on a Muslim's vineyard or crops as long as it is less than five wasq (approximately 653 kilograms)."
This hadith is sahih on the condition of Muslim, but the two Shaykhs did not record it.