(He was called from the right side of the valley, in the blessed place, from the tree: "O Musa! Verily, I am Allah.")28:30 However, here Allah says,
إِنِّى أَنَاْ رَبُّكَ
(Verily, I am your Lord!) meaning, `the One Who is talking to you and addressing you,'
فَاخْلَعْ نَعْلَيْكَ
(So take off your shoes;) `Ali bin Abi Talib, Abu Dharr, Abu Ayyub and others of the Salaf said, "They (his sandals) were from the skin of a donkey that was not slaughtered." It has also been said that he was only commanded to remove his sandals due to respect for the blessed spot. Concerning Allah's statement,
أَكَادُ أُخْفِيهَا (I would keep it secret - 20:15): Allah Ta` ala says that He wishes to keep the circumstances relating to the Day of Judgment hidden from all created things including prophets and angels. The word أَكَادُ (I would) gives a subtle hint that it is only to induce people to good deeds that the coming of the Day of Judgment has been disclosed, otherwise even this fact would have been concealed.
لِتُجْزَىٰ كُلُّ نَفْسٍ بِمَا تَسْعَىٰ (So that everyone is given a return for the effort one makes - 20:15). If this phrase is taken to be linked with the word آتِيَةٌ (has to come) then it would mean that this world is not a place of requital. Here a person does not receive recompense according to his merits and even if he receives some reward in this world it is just a token which does not constitute the full recompense of his deeds. It is, therefore, essential that there should be a time when everybody would receive his due reward.
Another possibility about the construction of this phrase is that it is taken to be linked with the words أَكَادُ أُخْفِيهَا (I would keep it secret - 20:15). In this case, it would mean that the philosophy in not revealing the time of death and the Day of Judgment is that people should continue in their endeavours and should not cease to strive in the belief that their own death or the Day of Judgment are still far away in the future. (Ruh)
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 10–15
Moses was born in Egypt. There, by some mischance, a Copt got killed by him. Thereafter, he left Egypt and went to Madyan. After he had spent many years there and was married, he decided to return to Egypt, taking along with him his wife and his flock of sheep. In the course of this journey, Moses passed through the Tur valley situated in the south of the Sinai peninsula. When night fell, he was unable to make out the way in the darkness. Moreover, it was winter time and the weather was bitterly cold. But soon he saw some far-off fire burning. Moses immediately set off in that direction to obtain some burning brands to keep them warm and also in the hopes of finding someone of whom he could ask the way.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.