اَلۡـحَـمۡـدُ   لِـلّٰـہِ  رَبِّ  الۡـعٰـلَـمِیۡنَ   وَ  الـصَّـلٰـوۃُ   وَ  الـسَّـلَامُ  عَـلٰی   خَاتَمِ النَّبِیّٖن

اَمَّـا  بَــعۡـدُ   فَـاَعُـوۡذُ   بِـا لـلّٰـہِ   مِـنَ   الـشَّـیۡـطٰنِ   الـرَّجِیۡمِؕ    بِـسۡمِ   الـلّٰـہِ   الـرَّحۡـمٰنِ   الـرَّحِـیۡمِؕ

The Lady of Paradise

اَلصَّلٰوةُ وَالسَّلَامُ عَلَيۡكَ يَا رَسُوۡلَ اللّٰه                                                                                                                        وَعَلٰى اٰلِكَ وَاَصۡحٰبِكَ يَا حَبِيۡبَ اللّٰه

اَلصَّلٰوةُ وَالسَّلَامُ عَلَيۡكَ يَا نَبِيَّ اللّٰه                                                                                                                                   وَعَلٰى اٰلِكَ وَاَصۡحٰبِكَ يَا نُوۡرَ اللّٰه

نَوَيۡتُ سُنَّتَ الۡاِعۡتِكَافِ

I make intention of Sunna iꜤtikāf.

Dear Islamic brothers! Whenever you enter the mosque, remember to make the intention of iꜤtikāf. As long as you remain in the masjid, you will continue to earn the reward of iꜤtikāf. Keep in mind that normally in a masjid, it is not permissible according to sharia for one to eat, drink, sleep, have suḥūr, ifṭār, or even drink Zamzam water or water upon which prayers have been recited. Yet, if you make the intention of iꜤtikāf, all these activities become permissible by extension. The intention of iꜤtikāf should not solely be for eating, drinking, or sleeping, but instead to please Allah Almighty.
As mentioned in Fatāwā Shāmī:

If someone wishes to eat, drink, or sleep in the masjid, they should make intention of iꜤtikāf, engage in the remembrance of Allah Almighty for a while, and then do as they wish (i.e., eat, drink, or sleep).