SB 11.27.9
arcayam sthandile ’gnau va
surye vapsu hrdi dvijah
dravyena bhakti-yukto ’rcet
sva-gurum mam amayaya
Translation:
A twice-born person should worship Me, his worshipable Lord, without duplicity, offering appropriate paraphernalia in loving devotion to My Deity form or to a form of Me appearing upon the ground, in fire, in the sun, in water or within the worshiper’s own heart.