The Prophet (ﷺ) said: “When any of you hears the call to prayer while he has a vessel (of food or drink) in his hand, he should not lay it down until he satisfies his need.”^[1]

Shaykh Muḥammad Nāṣir al-Dīn al-Albānī (رحمه الله) commented:
This hadīth indicates that if Fajr enters while a person is holding a vessel of food or drink, it is permissible for him [to finish what is in front of him] until he is satisfied. This is an exception to the (general understanding of the) verse:

وَكُلُوا وَاشْرَبُوا حَتَّىٰ يَتَبَيَّنَ لَكُمُ الْخَيْطُ الْأَبْيَضُ مِنَ الْخَيْطِ الْأَسْوَدِ مِنَ الْفَجْرِ

“And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night].”
[Al-Baqarah, 2:187].

Also, among the benefits derived from this hadīth is that it invalidates the innovated practice of imsāk (refraining from food and drink) a quarterhour before (the call to) Fajr. If they were aware of this concession, they would not fall into such an innovation. They only practice it out of fear that the call to Fajr will be made while they are still having suhūr.^[2]