قُلْ إِن كَانَتْ لَكُمُ الدَّارُ الْآخِرَةُ عِندَ اللَّهِ خَالِصَةً مِّن دُونِ النَّاسِ فَتَمَنَّوُا الْمَوْتَ إِن كُنتُمْ صَادِقِينَ
Qul in kaanat lakumud daarul aakhiratu 'indal laahi khaalisatam min doonin naasi fatamannawul mawta in kuntum saadiqeen
Say: if the home of the hereafter with God is yours alone, to the exclusion of all other people, then wish for death, if you are truthful.
The challenge is a test by proposal: if the claim of exclusive possession is true, then the thing claimed should be wanted rather than avoided. Tamannī is longing rather than seeking, so nothing is asked of anyone except a wish. The Qur'an uses this form of argument sparingly, and it works only because the claim it answers was about the hereafter and not about this life.