varaththAl vali ninaindhu mAdhava! nin pAdham
siraththAl vaNangkAnAm enRE? - uraththinAl
IrariyAy nEr valiyOnAya iraNiyanai
OrariyAy nI idandhadhu Un

Meaning:

nI idandhadhu 			- Did You rip
iraNiyanai 			- Hiranyakashipu's
Un 				- body,
uraththinAl 			- with Your great strength
Or ari Ay 			- in the form of the matchless Narasimha avatara,
Ir ari Ay 			- who was the enemy worthy of being split and
nEr valiyOn Aya 		- who had the strength to stand up and fight You,
vaNangkAnAm enRE 		- because he refused to bow
siraththAl 			- with his head
nin pAdham 			- at Your divine feet,
vali ninaindhu 			- thinking much of his strength
varaththAl 			- due to the boons from Brahma and other devatas? 
				  (No, it was done due to bhAgavata apachara).

Vyakhyana Saram:
In the previous pasuram, the Lord showed Azhvar flowers such as kAyA and pUvai, that are similar to Him, and saved him. As soon as He showed those to him, Azhvar remembers how he removed the enemy of Prahlada and saved him. Therefore, he talks about that in this pasuram.