Does stopping between "peace be upon you" and "and the mercy of Allah" in the Taslim invalidate the prayer?

Your prayer is valid and nothing is required of you, even if you omit the phrase "wa rahmatullah" (and the mercy of Allah) and suffice with "Assalamu alaykum" (Peace be upon you), as this is sufficient and completes the prayer. The obligatory part is "Assalamu alaykum" only, and anything added to it is sunnah (recommended) and not obligatory. We advise you to fear Allah and not to give in to whispers (waswasah). When you finish your prayer, say "Assalamu alaykum wa rahmatullah" to your right and to your left without hesitation.