This volume contains a detailed grammatical description of the dialects of Old Arabic attested in the Safaitic script, an Ancient North Arabian alphabet used...
Safaitic exists in a dialect continuum with Classical Arabic and some of its interesting (non-classical) features survive in modern Levantine Arabic:
Qaf ق becoming a glottal stop ء
Ẓa ظ becoming Ḍad ض
The pronunciation of the final ā in ى and ـه sound as ē.
Now while these features might have independently redeveloped in modern Levantine, to me it takes fewer steps to rationalize that these features attested in Safaitic between 2nd century BCE and 4th century CE in the Levant just continued into modern Levantine.
There are thousands of those inscriptions written here’s a database of it http://krc.orient.ox.ac.uk/ociana/index.php/database
Safaitic exists in a dialect continuum with Classical Arabic and some of its interesting (non-classical) features survive in modern Levantine Arabic:
Qaf ق becoming a glottal stop ء
Ẓa ظ becoming Ḍad ض
The pronunciation of the final ā in ى and ـه sound as ē.
Now while these features might have independently redeveloped in modern Levantine, to me it takes fewer steps to rationalize that these features attested in Safaitic between 2nd century BCE and 4th century CE in the Levant just continued into modern Levantine.