Regarding the saying: “My Lord! I have not worshipped You out of desire for Your Paradise, nor out of fear of Your Hellfire”, Al-ʿAllāmah Muḥammad Nāṣir al-Dīn al-Albānī comments:

Such speech does not emanate except from one who has not truly known Allāh—the Exalted and Most High—nor sensed His glory and might, magnanimity and generosity. Otherwise, (had he truly known Allāh and sensed His greatness), he would have worshipped Him hoping for what lies with Him: the eternal bliss (of Paradise). Foremost amongst its bliss is seeing Allāh, the Exalted. Likewise, he would have worshipped Him fearing what He has prepared for the sinners and unbelievers: the Hell-Fire and its everlasting, painful punishment. Foremost amongst its torment is that its people will be deprived of ever being able to see Allāh. As Allāh stated:

كَلَّا إِنَّهُمْ عَن رَّبِّهِمْ يَوْمَئِذٍ لَّمَحْجُوبُونَ

“No (the affair is not as they presume)! Indeed, that Day, they will be veiled from (seeing) their Lord.”
(Al-Muṭaffifīn, 83:15)

Because of this, the Prophets—may Allāh make good mention of them in the highest assembly of angels and grant them safety and peace—who are truly the most knowledgeable of creation about Allāh, would not converse to Allāh with the likes of such empty, idle speech. Instead, they would worship Him out of desire for His Paradise. How could they not when there lies within it what every Believer longs for, and that is the ability to see Him. Also, they would worship him out of fear of His Fire. Why would they not when its entrance necessitates that one is veiled, prevented and deprived of seeing Him. Due to this, after mentioning a selection of Prophets, Allāh says:

إِنَّهُمْ كَانُوا يُسَارِعُونَ فِي الْخَيْرَاتِ وَيَدْعُونَنَا رَغَبًا وَرَهَبًا ۖ وَكَانُوا لَنَا خَاشِعِينَ

“Indeed, they used to hasten on to do good deeds, and they used to call on Us with hope and fear, and used to humble themselves before Us.”
(Al-Anbiyāʾ, 21:90)