manners in Islam

10th of MUHARRAM ~ "When the Prophet [peace & blessings of Allah be upon him] came to Medina, he found (the Jews) fasting on the day of 'Ashura' (i.e. 10th of Muharram). They used to say: "THIS IS A GREAT DAY ON WHICH ALLAH SAVED MOSES [Peace Be Upon Him] AND DROWNED THE FOLK OF PHARAOH. Moses [Peace Be Upon Him] observed the fast on this day, as a sign of gratitude to Allah." The Prophet [peace & blessings of Allah be upon him] said, "I am closer to Moses than they." So, he observed the fast (on that day) and ordered the Muslims to fast on it." [Sahih Bukhari Vol 4, Book 55 #609]
Allah [Subhanahu wa Ta'ala] says (interpretation of the meaning):
“And We revealed to Moosa (Moses), saying: ‘Depart by night with My slaves, verily, you will be pursued.’
Then Fir‘awn (Pharaoh) sent callers to (all) the cities.
(Saying): ‘Verily, these indeed are but a small band.
And verily, they have done what has enraged us.
But we are a host all assembled, amply forewarned.’
So, We expelled them from gardens and springs,
Treasures, and every kind of honourable place.
Thus [We turned them (Pharaoh’s people) out] and We caused the Children of Israel to inherit them.
So they pursued them at sunrise.
And when the two hosts saw each other, the companions of Moosa (Moses) said: ‘We are sure to be overtaken.’
[Moosa (Moses)] said: ‘Nay, verily, with me is my Lord. He will guide me.’
Then We revealed to Moosa (Moses) (saying): ‘Strike the sea with your stick.’ And it parted, and each separate part (of that sea water) became like a huge mountain.
Then We brought near the others [Fir‘awn’s (Pharaoh’s) party] to that place.
And We saved Moosa (Moses) and all those with him.
Then We drowned the others.
Verily, in this is indeed a sign (or a proof), yet most of them are not believers.
And verily, your Lord, He is truly, the All‑Mighty, the Most Merciful” [The Qur'an, Surah Al-Shuara, 26:52-68]"
-->The 10th of Muharram ('Ashura) will fall on Wednesday, October 12th in most countries, however please do verify.
It is highly recommended to fast on the 9th and 10th of Muharram (or the 10th and 11th in case one is not able to fast on the 9th)