One verse

Srimad Bhagavatam 10.60.15

10.60.15

ययोरात्मसमं वित्तं जन्मैश्वर्याकृतिर्भव: । तयोर्विवाहो मैत्री च नोत्तमाधमयो: क्व‍‍चित् ॥ १५ ॥

yayor ātma-samaṁ vittaṁ janmaiśvaryākṛtir bhavaḥ tayor vivāho maitrī ca nottamādhamayoḥ kvacit

yayoḥ
of which two
ātma-samam
equal to oneself
vittam
property
janma
birth
aiśvarya
influence
ākṛtiḥ
and physical appearance
bhavaḥ
posterity
tayoḥ
of them
vivāhaḥ
marriage
maitrī
friendship
ca
and
na
not
uttama
of a superior
adhamayoḥ
and an inferior
kvacit
ever

Marriage and friendship are proper between two people who are equal in terms of their wealth, birth, influence, physical appearance and capacity for good progeny, but never between a superior and an inferior.