Attributed to Jesus of Nazareth
«Go ye into all the world, and preach the gospel to every creature… They shall take up serpents.»
Misattributed
Verdict
It is not in Jesus of Nazareth's work
It comes from the "longer ending" of Mark (16:9–20), absent from Sinaiticus and Vaticanus and unknown to Clement of Alexandria and Origen. It is regarded as a second-century addition harmonising Mark's abrupt ending with the other gospels.
Source: Metzger, Bruce M. A Textual Commentary on the Greek New Testament. 2.ª ed. Deutsche Bibelgesellschaft / United Bible Societies, Stuttgart, 1994.
What they did say
Verified words of Jesus of Nazareth
«The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.»
Marcos 1:15. Griego: SBLGNT; inglés: King James Version (1611); español: traducción propia.
«Blessed are the poor in spirit: for theirs is the kingdom of heaven.»
Mateo 5:3 (Sermón de la Montaña; Lucas 6:20 dice solo «los pobres»). Griego: SBLGNT; inglés: King James Version (1611); español: traducción propia.
«Love your enemies, do good to them which hate you.»
Lucas 6:27 (paralelo en Mateo 5:44; material de la fuente Q). Griego: SBLGNT; inglés: King James Version (1611); español: traducción propia.