Srila Bhaktivinoda Thakura has written five beautiful prayers in "Sri Navadvipa Bhava Taranga" for receiving the mercy of Lord Narasimha. These prayers are certainly assurance to all sincere devotees that the worship of Lord Narasimha is purely in the line of aspiring love and devotion to Sri Sri Radha and Krsna. Those prayers are as follows.
e dusta hrdaye kama adi ripu chaya
kutinati pratisthasa sathya sada raya
hrdaya-sodhana ara krsnera vasana
nrsimha-carane mora ei to' kamana
Within my sinful heart the six enemies headed by lust perpetually reside, as well as duplicity, the desire for fame, plus sheer cunning. At the lotus feet of Lord Narasimha, I hope that He will mercifully purify my heart and give me the desire to serve Lord Krsna.
kandiya nrsimha-pade magibo kakhana
nirapade navadvipe jugala-bhajana
bhaya bhaya paya yan'ra darsane se hari
prasanna hoibo kabe more daya kari
Weeping, I will beg at the lotus-feet of Lord Narasimha for the benediction of worshipping Radha and Krsna in Navadvipa, perfectly safe and free from all difficulties. When will this Lord Hari, Whose terrible form strikes fear into fear itself, ever become pleased and show me His mercy?
yadyapi bhisana murti dusta-jiva-prati
prahladadi krsna-bhakta-jane bhadra ati
kabe va prasanna ho'ye sa krpa-vacane
nirbhaya karibe ei mudha akincane
Even though Lord Narasimha is terrifying toward the sinful souls, He offers great auspiciousness unto the devotees of Lord Krsna headed by Prahlada Maharaja. When will He be pleased to speak words of compassion unto me, a worthless fool, and thereby make me fearless?
svacchande baiso he vatsa sri-gauranga-dhame
jugala-bhajana hau rati hau name
mama bhakta-krpa-bale vighna jabe dura
suddha cite bhajo radha-krsna-rasa-pura
He will say, "Dear child! Sit sown freely and live happily here in Sri Gauranga-dhama. May you nicely worship the Divine Couple, and may you develop loving attachment for Their Holy Names. By the mercy of My devotees, all obstacles are cast far away. With a purified heart, just perform the worship of Radha and Krsna, for such worship overflows with sweet nectar."
ei boli' kabe mora mastaka-upara
sviya sri-carana harse dharibe isvara
amani jugala-preme sattvika vikare
dharaya lutibo ami sri-nrsimha-dvare
Saying this, will that Lord delightedly place His own divine lotus-feet upon my head? I will experience sublime love for the Divine Couple Radha-Krsna and undergo the ecstatic transformations called sattvika. Falling on the ground, I will roll about at the door of Sri Narasimha's temple.
(Srila Bhaktivinoda Thakura, - "Sri Navadvipa Bhava Taranga", 36-40)