Check before drinking that no harmful thing is present in it. (Ithaf-us-Sadah liz-Zabeedi, vol. 5, pp. 594)

Recite ﴿اَلۡحَمۡدُ لِلّٰهِ﴾ after drinking.

Hujjat-ul-Islam, Sayyiduna Imam Muhammad Ghazali عَـلَـیۡـهِ رَحْـمَـةُ الـلّٰـهِ الۡـوَالِی has said: One should start drinking by reciting ﴿بِسۡـمِ اللّٰهِ﴾, recite ﴿اَلۡحَمۡدُ لِلّٰهِ﴾ at the end of the first breath, ﴿اَلۡحَمۡدُ لِلّٰهِ رَبِّ الۡعٰلَمِيۡنَ﴾ after the second breath and ﴿اَلۡحَمۡدُ لِلّٰهِ رَبِّ الۡعٰلَمِيۡنَ الرَّحۡـمٰنِ الرَّحِيۡمِ﴾ after the third breath.

(Ihya-ul-‘Uloom, vol. 2, pp. 8)

Leftover clean water of a Muslim should not be discarded.

It is reported that ﴿سُؤۡرُ الۡمُؤۡمِنِ شِفَاءٌ﴾ the leftover of a Muslim is a cure^[1].

After some moments of drinking water, if you observe the empty glass, some drops of water will be found collected at the bottom trickling down from its inner sides, drink them as well.

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