How do the causes differ between ʿImrān and Aḥmad?

Diptote Causes — Verb Patterns and Their Conditions

• Both are among the six nouns
• ʿImrān has sound plural, Aḥmad has genitive
• Both solely due to foreign origin
• Added alif-nūn for ʿImrān, verb pattern for Aḥmad