Why did he say "Mah Adaber"?
Rashi: What praises will I say in front of Him? He told me consolations (you will live), and did them!
Malbim: Why should I pray for naught? Refer to 38:15:2:2.
Why did he say "v'Amar Li"?
Radak: He told me via a Navi that I will live and enter Beis Hashem.
Malbim: Hashem already told me via a Navi "Mes Atah" (verse 1), "v'Hu Asah" - He made me mortally sick.
What is the meaning of "Adadeh Kol Shenosai"?
Rashi: This is like "va'Tidad Shenasi me'Einai" (Bereishis 31:40). I will lose all my sleep to praise you.
Rashi citing Targum Yonasan: [I will serve You] all my years [that You added to my life].
Radak: Adadeh is like 'ha'Ishah Medadeh Es Benah' (Shabbos 128b); she moves him little by little. So when a person recalls an affliction that came on him and he was saved from it, he moves his head.
Malbim: I thought about all my years, and I skipped the additional years that I should have lived [if not for my sin], as if they do not exist.
Why did he say "Al Mar Nafshi"?
Rashi: My soul was bitter [and You consoled it].
Radak: The bitterness of my soul, and I was saved from it.
Malbim: My bitter soul forgot its toil and began to prepare itself for its path [to death], the way of all the living.