I don't know about such rule, but yes, you can say both:

or

(Notice that there's no space between و and الأفعال. It's beside the point, but I'm obsessed with the details when it comes to the orthography :D)

This rule, if it does exist, only applies when the subject is in plural. If it's singular, then the verb must be conjugated in agreement with the subject's grammatical gender:

Not:

but:

Hello Ali how are you ?

How can I help you

@damngoodadvice

"Notice that there's no space between و and الأفعال. It's beside the point, but I'm obsessed with the details when it comes to the orthography :D)"

Haha, it's all good.

!ألف شكر

@damngoodadvice

My main concern was that I was reading ما يشترك فيه الأسماء والأفعال correctly, where الأسماءُ is الفاعل of يشترك and that it is مرفوع. No matter how long I have been reading and studying Arabic, I have those moments where my الوسواس القهري kicks in and I obsess about the small things, eventhough when looking at the sentence, the only logical conclusion would be that الأسماء is the الفاعل of يشترك. Thanks again for helping me in my madness. Haha

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