One verse

Srimad Bhagavatam 12.8.32

12.8.32

तस्यैवं युञ्जतश्चित्तं तप:स्वाध्यायसंयमै: । अनुग्रहायाविरासीन्नरनारायणो हरि: ॥ ३२ ॥

tasyaivaṁ yuñjataś cittaṁ tapaḥ-svādhyāya-saṁyamaiḥ anugrahāyāvirāsīn nara-nārāyaṇo hariḥ

tasya
while he, Mārkaṇḍeya
evam
in this way
yuñjataḥ
was fixing
cittam
his mind
tapaḥ
by austerity
svādhyāya
study of the Vedas
saṁyamaiḥ
and regulative principles
anugrahāya
for showing mercy
āvirāsīt
made Himself manifest
nara-nārāyaṇaḥ
exhibiting the forms of Nara and Nārāyaṇa
hariḥ
the Supreme Personality of Godhead

Desiring to bestow His mercy upon the saintly Mārkaṇḍeya, who had perfectly fixed his mind in self-realization through penance, Vedic study and observance of regulative principles, the Supreme Personality of Godhead personally appeared before the sage in the forms of Nara and Nārāyaṇa.