Is the hadith narrated by Mu'awiyah, may Allah be pleased with him, authentic, in which the Messenger of Allah, peace and blessings be upon him, commanded us not to connect one prayer directly to another without leaving or speaking in between? What does it mean? Does the second prayer become void when combining prayers if the worshipper immediately says the takbir for it after the taslim of the first? And why does the Tarawih prayer not become void when the Imam does that?

The aforementioned Hadith is authentic and contains a prohibition against connecting one prayer immediately with another until one speaks or leaves. The prohibition here does not mean entering into another prayer before completing the previous one with the taslim. The Prophet's (peace be upon him) prohibition against connecting two prayers indicates that the taslim is the end of the prayer. This prohibition is understood to be a recommendation, not an obligation, so if a worshipper connects one prayer with another, his prayer is valid. Connecting the rak'ahs of the Tarawih prayer does not fall under this prohibition.