The word: الْفِرْدَوْسِ (al-Firdaus) in: جَنَّاتُ الْفِرْدَوْسِ (Gardens of Firdaus) means a verdant valley full of fruits and flowers - with reference to Paradise. However, difference exists as to the origin of this word. Is it Arabic, or is it non-Arabic? Those who call it non-Arabic have to refine it further. Is it Persian or Greco-Roman or Syriac? There are different views about this.
It appears in the Sahih of al-Bukhari and Muslim that the Holy Prophet ﷺ said: 'when you ask of Allah, ask for Jannatul-Firdaus because it is the highest and the superior most rank of Jannah. Above it, there is the Throne of the Rahman and from it issue forth all streams of . Jannah.' (Qurtubi)