This is a saying from the Pali canon, upadhi dukkhassa mūlanti, which means “Attachment is the root of suffering.” So this is a genuine canonical quote.
You’ll find it in this sutta, but translated by Thanissaro as “Acquisition is the root of stress.” His translations are rather idiosyncratic.
In this translation of the same sutta it’s “acquisition is the root of suffering.”
Bhikkhu Bodhi’s translation (not available online, but in The Middle Length Discourses of the Buddha, page 868) has “attachment is the root of suffering,” although he sometimes has “acquisition” in place of “attachment,” in various repetitions of the phrase.
“He who can curb his wrath as soon as it arises, as a timely antidote will check snake’s venom that so quickly spreads — such a monk gives up the here and the beyond, just as a serpent sheds its worn-out skin.”
Without approval and without scorn, but carefully studying the sentences word by word, one should trace them in the Discourses and verify them by the Discipline. If they are neither traceable in the Discourses nor verifiable by the Discipline, one must conclude thus: ‘Certainly, this is not the Blessed One’s utterance; this has been misunderstood by that bhikkhu — or by that community, or by those elders, or by that elder.’ In that way, bhikkhus, you should reject it.
“Having gone on his almsround, the sage should then go to the forest, standing or taking a seat at the foot of a tree. The enlightened one, intent on jhana, should find delight in the forest, should practice jhana at the foot of a tree, attaining his own satisfaction.” The Buddha
The Buddha. (Source: Nalaka Sutta, Sutta Nipata.)