Comparison of a gold Dinar of the Caliph Abd al-Malik from 693 CE and a ceremonial coin of the Byzantine Emperor Constans II struck 652-654 CE. The connection with the fall of Mecca and the victory over the rival Caliph Abd Allah ibn Zubair in 692 CE.
CONSTANS II. 641-668 AD. AR Half Miliaresion or Siliqua (2.07 g, 6h). Constantinople mint. Struck 652-654 AD. d N CONSTAN TINUS PP AV, Constans, crowned and wearing chlamys, standing facing, holding globus cruciger.
In the 7th century, the silver Milaresion was no longer being issued except for very rare commemorative occasions. The obverse type of this ceremonial issue has only one parallel, in the follis of Constans dated Indictional year 11 (652/3 AD), struck at Syracuse (SB 1108), and is probably contemporary with the miliaresion issue (SB 986) with facing bust. It is uncertain if there is a specific event to be tied to these issues, and they may have simply been distributed to worthy members of the imperial court and important guests. Curiously, this standing figure seems to provide the closest design prototype for a unique miliaresion of Justinian II (SB 1257A) and the subsequent coin struck by the Umayyad Caliph Abd al-Malik in 693 CE (77 AH).
Any examples out there of the silver Milaresion of Justinian II (SB 1257A)?
However, the Byzantine Emperor Constans II was one of only two Byzantine Emperors (the other being his father Heraclius, d. 641 CE) who were known for their full, long beards on their coins. If the Muslim Caliph Abd al-Malik needed a prototype for a full bearded figure on a coin, this would have been it. However, there is absolutely no prototype for three figures on the obverse of a coin at this particular period.
These two Byzantine issues were unique, one-of-a-kind commemorative coins. This would also make them an appropriate model for a unique reigious / political statement: The power of the Sunni Umayyad Caliphate over the Shia rebels then current, a different "People of the House" (Pers. "Ahl-i-Bayt") than the Prophet Muhammad, his cousin and son-in-law Ali ibn Abu Talib, and his daughter Fatima, a Sunni version of this.
There was an even more critical reason to issue a commemorative coin in 693 CE with these particular individuals, the Prophet Muhammad flanked by Abu Bakr and Aisha: In 684 CE, Abd Allah ibn Zubair had proclaimed himself Caliph at Mecca. Abd Allah was a grandson of Abu Bakr's, and therefore the nephew of Aisha. His mother Asma bint Abu Bakr, Aisha's sister, was still alive, in her '90s. In some very important ways Abdullah had a much better claim to the Caliphate than the Umayyads, who had been the early enemies of Muhammad and the leaders of the pagan Meccan opposition to Islam. Mecca, the very heart of Islam, had been occupied for 9 years by a rival bitterly opposed to the Umayyads, who initially met with success in this civil war. Finally, in 692 CE, Mecca fell after a bitter siege, and Abd Allah was slain. The important thing is that Aisha, when she was alive, was the main backer of the Umayyads in the civil war against Ali ibn Abu Talib in the early 650's and the key figure in the Battle of the Camel, named indirectly after her, that forced Ali to negotiate. So here, we not only have a religoius / political statement against the Shia, but a clear statement of victory over Abdullah ibn az-Zubair, and a sign of the reunification of the House of Islam after many years of civil war, and the final recovery of Mecca for the Damascus-based Umayyad Caliphate.