The waiter was standing Friday. He had back pain.

.كان النادل يقف/ واقفًا يوم الجمعة، وأصبح لديه ألم في ظهره

we can rephrase it to:

وقف النادل طوال يوم الجمعة، وشعر بألم في ظهره.

Ben: May I ask you something as an English learner please?

When I read: "The waiter was standing Friday", it sounded weird to me, so my question is: Is it a common phrase that people say in the United State? I'm not saying it's wrong because obviously I'm still learning :) but to me it doesn't sound natural. I know you meant something like "the waiter was standing all day long" or "the waiter stood for long hours on Friday". Listening to native speakers sometimes, I just feel that they speak different English than the one we learn, and this is why I asked you my question.

The waiter was standing Friday. He had back pain.

,,,,,

النادل كان واقفاَ يوم الجمعه , كان لديه ألم في الظهر