Among the characteristics of Ramadan: the prescription of i'tikaf (spiritual retreat in the mosque) in it.

The Shaykh : Among the characteristics of Ramadan is that it is a recommended practice (sunnah) to perform i'tikaf (spiritual retreat in the mosque) in it, which means that a person must stay in the mosque for the worship of Allah (Mighty and Majestic), staying in the mosque for the worship of Allah. The evidence is that the Prophet (peace and blessings be upon him) performed i'tikaf (spiritual retreat in the mosque) in the last ten days of Ramadan. He had previously performed i'tikaf (spiritual retreat in the mosque) in the first ten days and then the middle ten days, seeking the Night of Decree. He was informed that it is in the last ten days, so he performed i'tikaf (spiritual retreat in the mosque) in the last ten days until Allah took his soul. However, does i'tikaf (spiritual retreat in the mosque) mean that companions gather in a corner of the mosque talking about trivial matters and things of no benefit, or is the intention to worship Allah (Mighty and Majestic)? The latter is the intention. For this reason, the scholars said in their definition of i'tikaf (spiritual retreat in the mosque): "It is staying in a mosque for the worship of Allah".
So beware of wasting these precious times by talking to your companions and wasting time. However, if you talk to them occasionally, there is nothing wrong with it, because the Prophet (peace and blessings be upon him) talked with his wife Safiyyah bint Huyayy (may Allah be pleased with her) at night, and then he got up to take her to her house. In any case, pay attention to this. Then, a person enters i'tikaf (spiritual retreat in the mosque) when the sun sets on the twentieth day of Ramadan, and he exits when the sun sets on the last day of Ramadan, whether it is the twenty-ninth or the thirtieth.