The earliest surviving reference to the Arabic term ‘God is great’ (Allāhu akbar) is in a Syriac text known as the Maronite Chronicle, composed in the second half of the 7th century, perhaps as early as the 660s. The anonymous chronicler describes a siege of Constantinople under the Arab commander Yazīd b. Mu‘āwiya; this may be the siege that Theophanēs and al-Ṭabarī place in 680, but the chronology is uncertain.
Chronicles can be hard to understand, so let’s summarise the story before reading it. At some point the Byzantine soldiers noticed that the Arab army was loosening the siege in order to plunder the surrounding area. They sortied against the scattered enemy and struck a victory. Emboldened, some people banded together the next day and made another sortie, against the advice of the emperor. This time, the Arabs were ready: they pretended to retreat, leading the Byzantines into a trap. The Arabs cried “God is great!” and charged. Here’s the full story:
“…Yazīd b. Mu‘āwiya went up again with a large army. While they were encamped in Thrace, the Arabs scattered for the purpose of plunder, leaving their hirelings and their sons to pasture the cattle and to snatch anything that should come their way. When those who were standing on the wall saw this, they went out and fell upon them and killed a great many young men and hirelings and some of the Arabs too. Then they snatched up the booty and went in to the City.
The next day, all the young of the City grouped together, along with some of those who had come in to take refuge there and a few of the Romans and said, ‘Let us make a sortie against them’. But Constantine told them, ‘Do not make a sortie. It is not as if you had engaged in a battle and won. All you have done is a bit of common thieving.’ But they refused to listen to him. Instead, a large number of people went out armed, carrying banners and streamers on high as is the Roman custom. As soon as they had gone out, all the gates were closed. The King [Constantine] had a tent erected on the wall, where he sat watching.
The Saracens drew them after them, retreating a good long way away from the wall, so that they would not be able to escape quickly when put to flight. So they went out and squatted in tribal formation. When the others reached them, they leapt to their feet and cried out in the way of their language, ‘God is great!’. Immediately the others turned tail in flight, chased by the Saracens, who fell on them, killing and making captives right up to the point where they came within range of the catapults on the wall. In his fury with them Constantine was barely willing to open the gates for them. Many of them fell and others were wounded by arrows.”
The text definitely says ‘God is great’, but the exact wording is uncertain due to a hole in the parchment toward the end of that term. The text says Alāhā rab— and is then interrupted. The full term may be Alāhā rab hū or Alāhā rabā.
I was reminded of this story while reading a source that is contemporary with it: the Armenian chronicle wrongly attributed to Sebeos, composed not long after 661. Pseudo-Sebeos is one of our earliest and most valuable witnesses to the Arab conquests and the ensuing civil war. What struck me is that he twice quotes the caliph ‘Uthmān (r. 644–56) as referring to “the great God”, a term that he does not attribute to any Christian or Jew.
The first instance is set in 652–3, when the Armenians rebelled against Byzantium and submitted to the Arabs. The “prince [išxan] of Ismael” – which I take to mean to the caliph ‘Uthmān – addressed a treaty to the Armenians, imposing regular tribute and a military alliance. Having recited the treaty’s stipulations, ‘Uthmān reportedly ended by saying, “I swear by the great God [mecn Astuac] that I shall not be false.”
The second instance in the chronicle is however set the year before, 651–2, when a peace treaty between the Arabs and Byzantium broke down. Now the “king [ark‘ay] of Ismael” – which, again, I take to be ‘Uthmān – sent the Byzantines a warning. “If you wish, he said, to preserve your life in safety, abandon that vain cult which you learned from childhood. Deny that Jesus and turn to the great God [Astuacn mec] whom I worship, the God of our father Abraham.”
Of course, I don’t think these purported quotations are actually quoting a treaty or a letter: for lack of evidence we should assume that the chronicler or his sources put words into the Arab ruler’s mouth. But it is striking that pseudo-Sebeos twice ‘quotes’ him referring to his god as “the great God”. Perhaps there is an echo of the Arabic formula Allāhu akbar.
But if we wanted to argue this, we would have to acknowledge that pseudo-Sebeos uses this term in one other place, and this time in a polytheistic context. When Bahrām Čōbīn (r. 590–1) seized the Sasanian throne, he wrote to the Armenian nobles, swearing by the Iranian gods that he would grant them a measure of autonomy: “If I shall be victorious, I swear by the great god [mec astuacn] Aramazd, by the lord Sun and the Moon, by fire and water, by Mihr and all the gods [astuacs], that I will give you the kingdom of Armenia, and whoever you wish you may make king for yourselves.”
Clearly, pseudo-Sebeos means this statement to be polytheistic. When he puts the same formula – swearing by “the great God” – into ‘Uthmān’s mouth, is he hinting that ‘Uthmān is pagan? I don’t think so. Pseudo-Sebeos, unlike some other early witnesses, does not portray the Arabs as pagans: he sees their religion as rooted in the Old Testament, and he attributes to them a belief that they share with the Jews a claim to the Holy Land through their common patriarch Abraham.
Although “the great god/God” (what a difference capitalisation can make!) is used for both a Zoroastrian and a Muslim ruler, I don’t think there’s any implied equivalence. In pseudo-Sebeos’ retelling, Bahrām Čōbīn acknowledges Aramazd (Ahura Mazda) as the highest god in the pantheon; ‘Uthmān, on the other hand, is calling his one and only god “the great God” without implicit comparison—except maybe to Jesus. Perhaps the slogan Allāhu akbar, attested by the Maronite Chronicler around the same time, influenced pseudo-Sebeos’ choice of words.
 On this text, see Palmer, West Syrian Chronicles, 29; Hoyland, Seeing Islam, 135–9; Penn, When Christians First Met Muslims, 54–7.
 Adapted from Palmer, West Syrian Chronicles, 32–3: parenthetical notes and parentheses marking the translator’s inference have been removed, and text has been broken into paragraphs. The emphasis in bold is of course mine. The corresponding Syriac edition is Brooks (ed.), Chronica Minora, vol. 2, 72–3. Cf. Nöldeke, “Zur Geschichte der Araber”, 92 and n. 1 = 97 and n. 4.
 On pseudo-Sebeos’ Chronicle, see Thomson, Armenian History Attributed to Sebeos, “Introduction”; Hoyland, Seeing Islam, 124–32.
 Abgaryan (ed.), Patmut‘iwn Sebeosi (1979), 164 = Thomson, Armenian History Attributed to Sebeos, 136.
 Patmut‘iwn, 169 = History, 143-4.
 Patmut‘iwn, 77 = History, 21.