One of the most famous and widely used books on the subject is "Matn Ibn Ashir" (The poem of Ibn Ashir) or just Ibn Ashir for short.

Ibn Ashir's full name is:
Abu Muhammad Abdulwahid Ahmad Bin Ali Bin Ashir Al-Ansari Al-Andalussi Al-Fassi.

He is a descendant of The Ansar, the tribes from Madina that gave full support to the Prophet Mohammad, peace and blessings of Allah be upon him.
His forefathers migrated from the Iberian Peninsula to Fes in Morocco.
He was born, brought up and buried in Fes.
He died Thursday afternoon 3rd of Dhi-Hijjah 1040 Hijra (~Thursday 3 July 1631 C.E.)

Hijra means migration. But here it means the migration of the Prophet from Makkah to Madina (City of the Prophet).
In dating preference is given to the Hijri calendar.
It is a reminder that one should migrate to what pleases our Creator and that it is a life struggle.

He studied under many scholars.
He reached a high level of mastery in sciences relating to the Qur'an, Hadith, Arabic language, logic, arithmetics, inheritance, astronomy etc.
He went for Haj (pilgrimage) to Makkah which was a long and dangerous journey in those days.
He was a doctor.
He was also a warrior.
He was a man who practiced what he learnt.

Matn Ibn Ashir covers the basic necessities which every one should know by the age of responsibility.

It is divided into three main topics:

1. Aqida which is a technical term for Iman.
It is an inward science that puts the heart at rest on firm foundations.

2. Fiqh which is a technical term for Islam.
It is an outward science that guides a person into the correct behaviour at any time and place. Its root lies in Iman.

3. Tassawuf which is a technical term for Ihsan.
It is based on aqida and fiqh and guides a person to be at its best at all times.

Muslims preserved the path that leads them back to the Prophet Mohammad, peace and blessings of Allah be upon him, in relating the sacred texts (Qur'an and hadith) as well as in understanding them.
Hence Ibn Ashir followed a path that leads to:

1. Al-Imam Al-Ashari in Aqida.
He died 330 (or so) Hijra (~941 C.E.)
He is a famous scholar from Baghdad.
He is a descendant of Abu Mussa Al-Ashari Al-Ansari the famous companion of the Prophet, peace and blessings of Allah be upon him, from Madina.

2. Al-Imam Malik in Fiqh.
He died Sunday Morning 14th of Rabi Al-Awal 179 Hijra (~Sunday 7 June 795 C.E.)
He is a famous Madina scholar.
He was a third generation scholar of Madina after the Prophet, peace and blessings of Allah be upon him.
He is the authority on many sciences taught in Al-Madina.

3. Al-Imam Al-Junaid in Tassawuf.
He died in 297 Hijra (~909 C.E.)
Al-Imam Al-Junaid is from Baghdad.
He is known as the master of sayings and practice among scholars.
His chain of transmission goes back to Al-Imam Ali, may Allah be pleased with him, the son in law and companion of the Prophet Mohammad, peace and blessings of Allah be upon him.

There is a lot more to say but i hope it is an opening for ears to hear, eyes to see and hearts to reflect.

Wassalam (Peace)