Is it permissible to cease the verbal ذكر (dhikr) if it becomes difficult to pronounce during prayer?

What is happening to you is from the work of Satan, so that he may corrupt your prayer and cast you into whispers that lead to abandoning prayer. Therefore, you must strive to pronounce the remembrance (dhikr) and the takbir in prayer, especially during the pillars and obligations. Do not pay attention to the instigations of Satan; rather, seek refuge in Allah from him and spit lightly to your left three times. For Allah the Almighty said: "And if an evil suggestion comes to you from Satan, then seek refuge in Allah. Indeed, He is the All-Hearing, the All-Knowing."