The third season is the ten days of Muharram

Prophet Mohammed ( peace be upon him ) informed the believers that Allah has given two occasions to be celebrated viz: Eidul-Fitr ( festival of breaking fast) and Eidul-Ad'ah ( festival of facrifice )
Muslims officially celebrate two occasions viz Eidul-Fitr ( that coms after Ramadan ) and Eidul-Ad'ha ( that comes after performing the fifth pillar of Islam, pilgrimage-Hajj.
Celebrations in Islam are blessings from Almighty Allah in that all of them come after accomplishing an act of worship.
Once during Eidul-Ad'ha, festival of sacrifice, Abu Baker-the first Caliph of Islam - visited Prophet Mohammed ( peace be upon him ) and found two maids singing and playing tambourrines. He reprimanded saying: "Do you play Satan's equipments in the house of the messenger of Allah ?" Prophet Mohammed ( peace be upon him ) woke up to Abu Baker's sound and said: "leave them alone Abu Baker ! Indeed every people have their own festival and this is our festival." ( Imam Muslim ) Our rightly guided ancestors used to glorify three religious seasons in that they would treble their acts of worship therein. Those seasons are:
The first 10 days of Dhul-Hijja ( the last month of the Islamic lunar calendar ) Abdullah Ibn Abbas naratted that Prophet Mohammed ( peace be upon him ) said: "There is no any other season where by acts of worship and devotion are dearer to Allah and more rewarding than these ten days of Dhul-Hijjah." His companions inquired: O messenger of Allah ! Even Jihad ? He replied: even Jihad, except for one who goes out fighting in Jihad then he gets martyred and in the process his belongings get used for Jihad purpose." ( Imam Al-Bukkhari )
In those days there is also the day of Arafah. Jabir bin Abdullah related that Prophet Mohammed ( peace be upon him ) said: "The day of Arafah is the best day of the year." ( rated sound by Imam Ibn Hibban ).
The second season is the last ten nights of Ramadan in which the Night of Power/ Destiny/Worth/ Honor falls. Allah says: The Night of Power is better than a thousand months (97:3 ).
The third season is the ten days of Muharram ( the first month of Islamic lunar calendar ). The day of Ashura in which Allah saved Moses from the Pharaoh and his army falls on the tenth of Muharram. If one fasts on this day he/she is forgiven the sins that he/she committed during the elapsed year.
Abu Huraira related that the Prophet Mohammed ( peace be upon him ) said: " The best month in which to fast after Ramadan is the month of Muharram. " This means that Muharram comes second to Ramadan in terms of trebled rewards that one gets for fasting. Ibn Taymiyya said. " The first ten days of Dhul-Hijjah are better than the days of Ramadan, whereas, the last ten nights of Ramadan are better than the last ten nights of Dhul-Hijjah."