Assalaamu alaykum wa rahmatullaahi wa barakaatuhu. In the morning and evening Athkaar (expressions of remembrance of Allah), should one recite 3 verses, meaning 17-19, of Surat Ar-Room, or it is only 2 verses, namely 17-18. May Allah reward you. Assalaamu alaykum wa rahmatullaahi wa barakaatuhu. Fee Amaanillaah.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

It is better to recite all 3 verses as they are part of the reported Athkaar that should be recited in the morning and evening. Imaam An-Nawawi said in his book Al-Athkaar:

"It was narrated in Sunan Abu Daawood that Ibn ʻAbbaas reported that the Prophet said, 'Whoever says in the morning: {So exalted is Allah when you reach the evening and when you reach the morning. And to Him is (due all) praise throughout the heavens and the earth. And (exalted is He) at night and when you are at noon. He brings the living out of the dead and brings the dead out of the living and brings to life the earth after its lifelessness. And thus will you be brought out.} [Quran 30:17-19], he will get that day what he has missed (of reward). And whoever says them in the evening, he will get that night what he has missed.'"

Allah knows best.