Matsyapurana 167.43

167.43

māṃ putrakāmaḥ prathamaṃ pitā te 'ṅgiraso muniḥ
pūrvamārādhayāmāsa tapastīvraṃ samāśritaḥ //

your father the sage Aṅgirasa adored Me with great devotion and asceticism with the intention of begetting a son Then, at the close of his asceticism, he sought a most illustrious son which boon I granted and by virtue of the same he was blessed with you as a son O, Mārkaṇḍeya who can by his Yogic power see me dabbling like a boy at a period like this, unless He is blessed by me?"—41-45