1)
Why did he mention his tongue?
1.
Radak: Since he mentioned the lips, he mentioned also the tongue. Both of them are used to form words.
2.
Malbim: The tongue refers to speech via the intellectual Nefesh. Also it will delve to investigate Tzidkasecha!
2)
Why did he say that Mevakshei Ra'asi will be shamed?
1.
Radak: They will be shamed, and I will sing!
2.
Malbim: This was via Your many miracles.
