The virtues of fasting the Day of `Āshūra. or the 10th day of Muḥarram are widely known to many, as millions of Muslims all over the world fast this day in the hope that it will atone for their sins for the previous year. As the Prophet (saw) said:
It will expiate the sins of the past year. 
In light of this, the story of the Prophet (sall Allāhu ʿalayhi wa sallam)’s interactions with the Jews in Madinah comes to mind, as it is similarly well known and quoted alongside other hādith that they would also fast on this day. Hence the Prophet (sall Allāhu ʿalayhi wa sallam) commanded us to fast an additional day in order to distinguish the Muslims from other religions.
Ibn Abbas (raḍī Allāhu anhu) reported:
The Messenger of Allāh, peace and blessings be upon him, came to Medina and he found the Jews fasting on the day of Ashura. The Prophet said, “What is this day you are fasting?” They said, “This is a great day in which Allāh saved Moses and his people, and he drowned Pharaoh and his people. Moses fasted on it due to gratitude, so we also fast on it.” The Prophet said, “We have more of a right to Moses and are closer to him than you.” The Prophet fasted the day of Āshūra and he commanded fasting on it.” 
The Jews of Madinah were following the tradition of Mūsā (ʿalayhi al-Salām) to fast the day on which Allāh (subḥānahu wa taʿālā) saved him and his people from Firaun. The Prophet (sall Allāhu ʿalayhi wa sallam) is telling us that we as Muslims have more of a right to Mūsā (ʿalayhi al-Salām) than them, and thus commanded us to fast on this day. He (sall Allāhu ʿalayhi wa sallam) is informing us that the legacy of Mūsā (ʿalayhi al-Salām) belongs to this ummah.
However, is this magnificent legacy that we have inherited limited to following a single tradition of his in fasting the day of `Āshūra? Or does our right to Mūsā (ʿalayhi al-Salām) extend beyond such a limited understanding?
If we truly wish to commemorate the vanquishing of Firaun and his army, and the salvation of Mūsā (ʿalayhi al-Salām) and his people, we must remember the background to this glorious day and the events that preceded it. Allāh (subḥānahu wa taʿālā)’s miraculous intervention did not occur in a vacuum but was the pinnacle of a series of interactions between Mūsā (ʿalayhi al-Salām) and Firaun.
In doing so, we can take away at least three powerful characteristics of Mūsā (ʿalayhi al-Salām) that we should strive to implement in our daily lives.
1. Speaking Truth to Power
Firstly, we must recognize the courage of Mūsā (ʿalayhi al-Salām) in speaking truth to power. The only reason that Firaun and his army were chasing Mūsā (ʿalayhi al-Salām) and the Bani Israil on the day of `Āshūra was because Mūsā (ʿalayhi al-Salām) had challenged his claim to lordship, his tyranny, and his enslavement of the Bani Israil. Mūsā (ʿalayhi al-Salām) did all this despite the incredible natural fear that festered inside him from standing up to such a tyrant. That anxiety of confronting this powerful king who ruled with a god-complex could only have been immeasurably magnified by Mūsā (ʿalayhi al-Salām)’s speech impediment, his status as a second class citizen, and his having an arrest warrant issued against him for murder. Yet, he was able to overcome all of this to boldly walk into the court of Firaun and warn him of his wrongdoing. Remarkably, this was not an isolated incident, and Mūsā (ʿalayhi al-Salām) persisted in speaking truth to power over a significant period of time regardless of the taunts and threats that Firaun threw his way.
The legacy we have inherited mandates that we make it part of our character to have this type of courage, to speak truth to power, and to not shy away from it out of fear for our personal safety or potential difficulties we may face as a result of doing so. As the Prophet (sall Allāhu ʿalayhi wa sallam) advised us, “the best jihad is a word of truth before a tyrant ruler.” 
2. Exert your maximum effort
Secondly, we learn that Allāh (subḥānahu wa taʿālā)’s miraculous intervention occurs after Mūsā (ʿalayhi al-Salām) has exhausted his absolute maximum efforts to fulfill Allāh (subḥānahu wa taʿālā)’s commands. It comes after a period of time during which he has advised the Bani Israil, spoken out against Firaun’s tyranny on numerous occasions, competed with the magicians, and taken his people out from Egypt. It is at the point where they are between death by drowning and death by the sword that Allāh (subḥānahu wa taʿālā) fulfills His promise and causes the sea to part to enable their escape. Even at this point as if to emphasise the point, Allāh (subḥānahu wa taʿālā) commands Mūsā (ʿalayhi al-Salām) to strike the sea with his staff so there is literally nothing more he can do after this except wait for Allāh (subḥānahu wa taʿālā)’s help.
When we witness injustice and oppression around us, whether from the state and its machinations or from elements within our societies, it is not from the legacy of Mūsā (ʿalayhi al-Salām) to silently condemn it and to simply pray for Allāh (subḥānahu wa taʿālā)’s help.
3. Having trust and certainty in Allāh
Finally, and most importantly, the legacy of Mūsā (ʿalayhi al-Salām) requires us to have unwavering trust and certainty in the promise of Allāh (subḥānahu wa taʿālā). Even when Mūsā (ʿalayhi al-Salām) was trapped between the sea and Firaun and his army, with thousands of men, women, and children on the verge of being slaughtered, and with the naysayers amidst his people complaining that they were doomed, his faith in Allāh (subḥānahu wa taʿālā) remained as strong as ever. He vision was not limited to the tangible things his eyes could see but was guided by his heart which was attached to Allāh (subḥānahu wa taʿālā) and His promise.
No! Indeed, with me is my Lord; He will guide me. 
As believers and inheritors of the legacy of one of the greatest prophets to walk the face of this earth, we must continue this great tradition of speaking truth to power which entails devoting ourselves to the cause and maximizing our efforts and always having a firm, resolute faith that Allāh (subḥānahu wa taʿālā) will give us victory. This is the real legacy of Mūsā (ʿalayhi al-Salām) that we should be striving to replicate in our lives.