When should one stop eating and drinking? And what is the ruling on one who has the vessel in his hand when hearing the adhaan?

The question of when to stop eating and drinking in relation to the call to prayer (adhan) is addressed in the hadith literature. The Prophet Muhammad ﷺ instructed to ensure that individuals have sufficient time to complete their meals and drinks prior to the commencement of the prayer. Specifically, Sunan al-Tirmidhi states: The Prophet told Bilal, 'When you call to prayer, prolong your voice; and when you give the iqama, shorten it. Space the time between adhan and iqama enough for the eater to finish his meal, the drinker his drink, and the person answering the call of nature to complete his need. Do not stand for prayer until you have seen me.' Sunan al-Tirmidhi 2:47SunniVery Daif (per Al-Albani).

This guidance indicates that one should ideally stop eating and drinking when the call to prayer is heard, but there is an allowance for finishing what one is eating or drinking if there is sufficient time before the prayer begins. The intention is to ensure that individuals are not rushed and can fulfill their needs before engaging in prayer.

As for the ruling on someone who has the vessel in hand when hearing the adhaan, it is generally understood that they should complete their act of eating or drinking, as the hadith emphasizes not interrupting what one is doing until it is appropriate to do so. The Prophet ﷺ also mentioned: If one of you hears the call to prayer and is holding food or drink, he should not put it down until he finishes what he was doing with it. Sunan Abu Dawud 14:38SunniHasan Sahih (per Al-Albani).

In summary, individuals should stop eating and drinking upon hearing the adhaan, but they are allowed to finish their meal or drink if they are in the midst of it, emphasizing the importance of mindfulness and preparation for prayer without undue haste. For specific rulings and guidance, it's best to consult a qualified local scholar.