On why, when u understand moksha or mukti, you need to practice in a certain way,as your guru intends. Below, Ramana Maharishi also believes practice is an important stage when you are yet looped in the vicious grip of samskaras:
Unless the samskaras cease to exist, there will always be doubt and confusion. All efforts are directed to destroying doubt and confusion. To do so their roots must be cut. Their roots are the samskaras. These are rendered ineffective by practice as prescribed by the Guru. The Guru leaves it to the seeker to do this much so that he might himself find out that there is no ignorance. Hearing the truth [sravana] is the first stage. If the understanding is not firm one has to practise reflection [manana] and uninterrupted contemplation [nididhyasana] on it. These two processes scorch the seeds of samskaras so that they are rendered ineffective.