The current Salah first so that you wouldn’t be praying two missed prayers!

If I had one missed Salaah to make up (just one) but I think that it is quite likely that if I make up that Salaah, then the time for the current Salaah will be over. Should I pray the current Salaah first or the missed one?

Prayer | September 23, 2015 3:44 am
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When I pray, my sleeves fall down a bit. Is it permissible to cover half my hands in prayer? Because I have cut holes in my prayer dress for my thumbs to fit through to stop my sleeves from falling.
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It is narrated from Khalid Al-Hadhdha’ that Abu Qilaba arrived while the Imam was delivering the sermon. He sat down and did not perform any prayer (Sharh Ma’ani ‘l-athar 1:369). Doesn’t this narration indicate that praying salaah *(upon arriving at the masjid) during the Friday khutbah is wrong?