1)
What do we learn from "Az Nasan David b'Rosh"?
1.
Malbim: They praised with many Psalms, just David fixed these two at the beginning.
2)
What was "b'Yad Asaf"?
1.
'Rashi': It was a musical instrument called ha'Yados - "veha'Leviyim? Matanyah Al ha'Yados."
3)
What do we learn from "Asaf v'Echav"?
1.
'Rashi': Asaf began "Hodu la'Shem Kir'u vi'Shmo", and all his brothers responded. This is like "Matanyah? ben Asaf Rosh ha'Techilah Yehodeh la'Tefilah" (Nechemyah 11:17).
