utthāyotthāya kṛṣṇasya
cirasya pādayoḥ patan
āste mahitvaṁ prāg-dṛṣṭaṁ
smṛtvā smṛtvā punaḥ punaḥ
utthāya utthāya - rising repeatedly; kṛṣṇasya - of Lord Kṛṣṇa; cirasya - for a long time; pādayoḥ - at the lotus feet; patan - falling down; āste - remained; mahitvam - the greatness; prāk-dṛṣṭam - which he had previously seen; smṛtvā smṛtvā - remembering and remembering; punaḥ punaḥ - again and again.
As stated in one prayer,
śrutim apare smṛtim itare
bhāratam anye bhajantu bhava-bhītāḥ
aham iha nandaṁ vande
yasyālinde paraṁ brahma
“Let others study the Vedas, smṛti and Mahābhārata, fearing material existence, but I shall worship Nanda Mahārāja, in whose courtyard is crawling the Supreme Brahman. Nanda Mahārāja is so great that the Parabrahman is crawling in his yard, and therefore I shall worship him.” (Padyāvalī 126)
Brahmā was falling down in ecstasy. Because of the presence of the Supreme Personality of Godhead, who exactly resembled a human child, Brahmā was naturally astonished. Therefore with a faltering voice he offered prayers, understanding that here was the Supreme Person.