In plain words
Precisely because he was a disciple of such firm faith, Śaṅkara appointed Toṭaka head of the pīṭha at the place called Badri. Four came to be Śaṅkara's special first disciples. Padmapāda, Sureśa, Toṭaka and Hastāmalaka: these four stood as his first disciples. To establish the spiritual doctrine of Advaita in the four corners of our Bhārata, he appointed these four as four pīṭhas, and placed these four disciples in the seat of authority over the four pīṭhas. That Maṇḍanamiśra they also went on calling Sureśa. Śaṅkara debated with this Maṇḍanamiśra in every kind of learning, won the victory in that śāstra, won the contest he had entered with Maṇḍanamiśra, and gave the householder Maṇḍanamiśra the sannyāsa āśrama. His wife was none other than Ubhayabhāratī. Maṇḍanamiśra had grasped well all the śāstras and all the Vedas too. Truly, he can be called nothing less than an embodiment of Jñāna. He can also be called a home of learning. What kind of guru's teaching Śaṅkara gave a disciple who had received such sacred training is a matter we must enquire into well. It is precisely because such guruhood, or such discipleship of one-pointed citta, is not to be found today that this state of things has come upon Bhārata.
Listening and Practice
Teachings are of two kinds. One kind tells by word of mouth, changes the mind and sets it into conduct. Now, through teaching, you listen and can make an effort to change your mind somewhat. It is hard for that to come even a little into practice. Then the second way: doing it yourself, showing it to others and making the effort to have them do it, that is the second way. When we do it, the one who follows gains the good sense to merge his every limb in it. Through telling, merely the ears, and nothing more, are pleased; it carries as far as the heart, and then it disappears. Now Śaṅkara did not readily accept the ślokas his disciples composed with their great skill of intellect; he went on examining each śloka, to find out its inner meaning and what its author intended.