Many historians said that Imam al-Rida, peace be on him, was brown or deep brown.[1]It was said that he was white had a medium height,[2]and that he was like his grandfather Allah’s Apostle, may Allah bless him and his family.[3] s he was like his grandfather in his characteristics, he was similar to him in his noble moral traits, which distinguished him from the other prophets.

His Solemnity
As for the solemnity of Imam Abu Mohammed (al-Rida); faces were humbled in fear of it, for it was similar to that of the prophets and the testamentary trustees (of authority) whom Allah clothed in His light. All those who saw him respected him. An example of his solemnity was that when he sat with the people or rode off with them, none was able to raise his voice because of his great solemnity.[4]The reporters have said: “When he (i.e. Imam al-Rida, peace be on him) came to al-Ma’mun, the chamberlains and the servants hurried to raise the curtain for him. When they heard that al-Ma’mun wanted to pledge allegiance to him, they said to each other that if he (the Imam) came, they would not honor or magnify him as they would do. The Imam came as usual, and his solemnity moved them, so they honored him as they would do. Then they blamed one another and swore (by Allah) that if he returned they would not honor him. When the Imam, peace be on him, came on the following day, they stood for him and greeted him, but they did not raise they curtain for him, so a wind came and raised it for him. When he wanted to leave, the wind also raised the curtain for him.As a result they said to each other: ‘Surely this man is of great importance, and Allah takes care of him, so return to your serving him.’[5]"
The Imams of the Household (of the Prophet), peace be on them, had importance and standing with Allah, the Most High, for it was He who supported and directed them to correctness, as He did toward His prophets and His messengers.

The Inscription of his Ring
As for the inscription and words engraved in ring, theymore likely represent one’s inclinations and desires. The following (words) were engraved in the ring of Imam al-Rida, peace be on him:
Wali Allah (the Friend of Allah).[6]
He had another ring in which it was engraved:
Al-‘Izzah Lillah (Might belongs to Allah).[7]
These inscriptions represent the Imam’s great devotion to Allah, the Most Exalted, and his clinging to Him.

His Childhood
Imam al-Rida, peace be on him, grew up in the greatest and most exalted house in Islam. It was the house of the Imamate and center of revelation. The house which Allah permitted to be exalted and in which His name may be remembered. Imam al-Rida grew up in this noble house dominated by high Islamic education. For wherein the young respected and honored the old, and the old felt compassion for the young; noble moral traits spread; nothing was heard except reciting the Book of Allah; and nothing was done except good deeds and what brought man near to his Lord.
Educationists have maintained that house is among the most important factors which form person and build his character. If love, friendship, exalted habits, good customs, and sweet words dominate house, child will grow up soundly, be far from complexity and double personality. If house is corrupt and is full of hatred and detest, child will be complex and corrupt.
As for the house where Imam al-Rida, peace be on him, grew up, it was the most exalted one in the world of Islam, for it was the center of virtue and noble moral traits;it brought up the best of mankind and the Imams of truth and justice in Islam. In addition to house, environment plays an important role in bringing up person. As for the environment in which Imam al-Rida, peace be on him, grew up, it included the best men and scholars who studied under his father Imam Musa b. Ja‘far, peace be on him. All intellectual factors and means of exalted education were available for Imam al-Rida, peace be on him, so he grew up within this educational frame just as his great fathers (the treasures of Islam) did.

His Behavior
As for the behavior of Imam al-Rida, peace be on him, it was a wonderful example of his fathers, who dined their souls and freed them from every inclination which had no relation with truth and reality.
The behavior of Imam al-Rida, peace be on him, is distinguished by showing steadfastness toward the truth and rejecting falsehood. He ordered al-Ma’mun, the ‘Abbasid Caliph, to fear Allah and blamed him for his behavior which opposed the reality of religion. However, al-Ma’mun became displeased with the Imam and committed the most horrible crime when he assassinated him, peace be on him. We will explain this matter in the chapters that follow.
The Imam’s behavior toward his household and his brothers is another example of his showing steadfastness toward the truth. The Imam turned away from those who deviated from Allah’s laws. He swore (by Allah) that he would not speak with his brother Zayd until he met Allah, the Most High. That was when Zayd committed something contrary to Allah’s law.
As for his behavior toward his children, it is distinguished by his showing marvelous, educational manners toward them, especially toward his son Imam al-Jawad, peace be on him. He did not call him with his name; rather he addressed him with his kunya. He said: “Abu Ja‘far (al-Jawad) wrote to me, and I wrote to Abu Ja‘far.[8]" He called him with his kunya because he wanted to honor and magnify him.

Sources:
[1]Akhbar al-Diwal.
[2]Al-Shaykhani al-Qadiri, al-Sirat al-Sawi fi Manaqib Al al-Nabi, p. 199.
[3]Al-Durr al-Nazïm, p. 210.
[4]Hayat al-Imam al-Jawad.
[5]Akhbar al-Diwal, p. 114. Jawhart al-Kalam, p. 145. Al-Ithaf bi Hub al-Ashraf, p. 58.
[6]Al-Durr al-Masluk, p. 139. Al-Majjlisi, Bihar al-Anwar, vol. 12, p. 4.
[7]Al-Durr al-Nazïm, p. 210.
[8]Mu‘jam Rijal al-Hadïth, vol. 14, p. 283.