Hilchot Issurei Biyah
“shelo yiso zoken yalda shedovor zeh gorem l’znus”
an old man shall not marry a young woman as this will lead to adultery
Yevamot 101b
“k’lech etsel shekmosech ve’al tachnis ketata letoch beisech”
a man shall marry a woman of his age and not bring strife into his home