In this month, it is prohibited to fast the 13th.
You fast 14 and 15 and this is an exception

Sheikh,I saw in one of your posts that it is forbidden to fast on 10 11 12and 13 of Dhul Hijja. But the white days (Ayyamul Beeyd) – 13th, 14th and 15th are equally recommended… Please help clarify.

Fasting | September 1, 2017 6:33 am
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The Prophet said that if a fast the day of Arafat the bad deeds of last year and coming year will be forgiven , then one can fast on Arafat and keep committing sins for the next year as they will be forgiven due to fasting in Arafat.
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Can one eat or drink with the azaan or one should stop drinking eating when the first word of azaan is heard?