Do you understand the difference between the point being made by this scholar and plagiarism?
"From a literary point of view, we should talk of Qur’ānic Psalms, as well as Qur’ānic madrāšē, memrē, and soḡiyāthā72. I don’t mean that the texts I am inclined to call Qur’ānic Psalms, madrāšē, and so on, are a servile borrowing of Syriac literary traditions – far from that: they are adapted, not without creativity, to the context of Arabic language and literature (e.g. Syriac verse is based on syllabic count, contrary to Arabic poetry and Arabic saǧ‘). But – and this is crucial –, they share compositional features with their Syriac/Aramaic homologs, they draw from them a good part of their verbal, phraseological and thematic repertoire, and, also, they play a similar role: they are suited for narrative or paraenetic compositions, and they are used in homiletic or liturgical settings. Indeed, a good number of Qur’ānic pericopes look like Arabic ingenious patchworks of Biblical and para- Biblical texts, designed to comment passages or aspects of the Scripture, whereas others look like Arabic translations of liturgical formulas.
This is not unexpected if we have in mind some Late Antique religious practices, namely the well-known fact that Christian Churches followed the Jewish custom of reading publicly the Scriptures, according to the lectionary principle. In other words, people did not read the whole of the Scripture to the assembly, but lectionaries (Syriac qǝryānā, “reading of Scripture in Divine Service”, etymon of Arabic qur’ān), containing selected passages of the Scripture, to be read in the community. Therefore, many of the texts which constitute the Qur’ān should not be seen (at least if we are interested in their original Sitz im Leben) as substitutes for the (Jewish or Christian) Scripture, but rather as a (putatively divinely inspired) commentary of Scripture. And since this Scripture was not in Arabic, we understand better the role of the Qur’ān, and we also understand better why it insists so much on Arabic (Q 12:2; 13:37; 14:41; 16:103; 26:195; 39:28; 41:3, 44; 42:7; 43:3; 46:12): stressing that there is an Arabic qur’ān supposes that there might be non-Arabic scriptures." Guillaume Dye - Traces of Bilingualism/Multilingualism in Qur’ānic Arabic