RasulAllah (saww) said: “A part of me will be buried in the land of Khorasan. God the Highest will surely remove the sorrows of any sorrowful person who goes on the pilgrimage of Imam Al-Ridha (as). God will surely forgive the sins of any sinful person who goes on pilgrimage to his shrine”. 
The Blessed 8th Imam was born in Medina on the 11th of Dhulqa’dah 148AH (765 AD). He was one of 37 children of the 7th Imam; Musa al-Kaadhim (as), and his mother was a pious lady from North Africa whose name is said to be Arwa also known as Umm Al-Baneen.
His kuniya was Abu Al-Hassan and his title Al-Ridha (the one who is satisfied) is said to be awarded to him because he was always satisfied with Allah (swt)’s decree; (al raadhi bil qada’ wal qadhar).
He spent his childhood and youth with his beloved father, after which Harun Al-Rashid, the Abbasid ruler, imprisoned the 7th Imam. During the 7th Imam’s imprisonment, Imam Al-Ridha (as) took on the responsibility of looking after the Hashimiyeh household as well as the community. The 7th Imam was eventually poisoned by Harun and upon his martyrdom the 8th Imam, at the age of 35, assumed the responsibility of Imamah – which lasted for a period of approximately 20 years.
Imam Al-Ridha (as) spent about a decade under the tyranny of Harun, who had two sons; Ameen and Mamoon. The mother of Ameen, Zubaydah, placed much pressure on Harun to ensure that he appointed Ameen as his successor upon his death. Ameen succeeded the throne but it was very short-lived as Mamoon killed his brother to claim the position of ruler-ship. This put Mamoon in a difficult position as members of the Abbasids turned against him along with others. Thus, to secure his name and position, Mamoon decided to appoint the 8th Imam as his “crown prince”.
Imam al-Ridha (as) was threatened by Mamoon, so the Imam accepted only on conditions which were written down and agreed upon by Mamoon. The 8th Imam thus made his way to Khorasan Iran, which is where Mamoon was based, and along the way passed the city of Neshapur where thousands upon thousands of people came to welcome the Imam on the outskirt of the city. It was here, upon the request of the residents for advice from the Imam, that the Imam narrated the golden chain of hadith (silsilat al-thahabiyyeh): “I heard my father Musa ibne Jaafar (as) say that I heard my father Jaafar ibne Muhammed (as) say that I heard my father Muhammed ibne Ali (as) say that I heard my father Ali ibne al-Hussain (as) say that I heard my father Hussain ibne Ali (as) say that I heard my father Amir al-Mu’mineen Ali ibne Abi Talib (as) say that I heard RasulAllah (saww) say that I heard Jibraeel (as) say that I heard God say that the sentence ‘There is no God but God is my stronghold, thus whomever enters my stronghold shall be safe from my punishment.’” Imam al-Ridha then said: “This has its conditions, and I myself am one of those conditions.”
The Imam was appointed as the successor of Mamoon in the year 201 AH (816 AD) and a grand feast was held to celebrate the occasion on the 6th of Ramadan. All this aided Mamoon to stabilise his position and win the support of those that had gone against him after he killed his brother Ameen, hence his plan was a success – or so he thought.
Imam Al-Ridha’s knowledge knew no limits. He compiled ‘The golden treatise’ (al-risalah al-thahabiyyeh); a dissertation on anatomy, functions of organisms, ailments – diagnosis and treatment. Some of the advice from the dissertation included: 
– Not to eat eggs and fish together as it can cause arthritis, colic, piles or tooth ache.
– Drink water at the end of a meal as consumption of it whilst eating slows down the functions of the stomach.
– Sleep affects the brain, train the brain to have mindful rest and make a habit of waking 2 hours before daybreak.
Amongst his other pearls of wisdom were: 
– Asking forgiveness from Allah (swt) is like shaking a tree to make its leaves fall
– Be truthful and avoid telling lies.
– The excellence of the congregational prayer, comparing with solitary prayer, is one rakaat to two thousand rakaats
His virtues included: 
Ebrahim ibne al-Abbas narrated – “I have never seen Al-Ridha (as):
– Hurt anybody with something he said,
– Interrupt anyone until they had finished what they were saying,
– Refuse to do someone a favour that he was able to do.”
The beautiful nature of Imam Al-Ridha (as), coupled with his unmatched knowledge, caused the people to love and respect him immensely. In no time the popularity of Imam Al-Ridha (as) began to rise to such an extent that Mamoon felt threatened and did his utmost to diminish the honour of the Imam by attempting to humiliate him on many occasions. However, through the grace and wisdom that Allah (swt) had bestowed upon our holy Imam, Mamoon’s attempts were to no avail. He soon realised that he had made a tremendous mistake by appointing the Imam as his successor, and thus decided to poison and kill him.
The Imam was martyred and died in Khorasan at the age of 55 in the year 203AH (818 AD). His son, Imam Al-Jawad (as) was around 7 years of age at the time.
Imam Al-Ridha (as) is the one who established the majalis & mourning for Imam Al-Hussain (as). He is said to have told one of his companions: “Oh ibn Al-Shabeeb, if you are going to cry for anything, cry for Hussain (as), for he was slaughtered the way a sheep is slaughtered.” It was also our 8th Imam who first began the tradition of placing the hand on the head when mentioning the name of our awaited saviour Imam Al-Mahdi (atf).
Imam Al-Ridha (as) is known to have also said “One who refrains from seeking his (worldly) desires on the day of Ashoora, Allah (swt) shall grant him his desires of his world and the hearafter.”
Peace be upon thee, O Imam Al-Hussain!
Peace be upon thee, who lies far away from his domain, O Ali son of Imam Musa Al- Ridha!
Peace be upon thee, O aba Salih al-Mahdi, O king of the times…
Assalamu alayka ya Aba Abdillah Al-Hussain!
Assalamu alayka ya ghareeb al ghurbaa, ya Ali ibne moosa Al-Ridha!
Wa Assalamu alayka ya aba Salih al-Mahdi, ya Sahib Al-Zamaan…
Kitab al-irshad by Shaykh al-mufid
Lectures by: Shaykh Usama al-Attar, Sayyed Mahdi Modarresi,
 al-risalah al-thahabiyyeh translated by P.E.T publications, original source: Bihaar al anwaar by Allamah Majlisi
 A bundle of flowers by Ayatullah Sayyid Kamal Faghih Imani
 Odattol Daee by Allamah Hilli
 The scale of wisdom by Muhammadi Rayshari
 Bihaar al anwaar by Allamah Majlisi
 Nuqushe Esmat by Allamah Jawadi
 Wasa’il Al-Shia