What is the authenticity of the hadith: "The Kaaba was a خشْفة [a piece of wood or an ark] upon water two thousand years before the earth, and upon it were two angels glorifying [Allah] night and day"? And is it to be understood from this that the creation of night and day preceded the creation of the earth and the heavens?

The narration about the- Kaaba being created two thousand years before the Earth is attributed to Abu Hurairah (may Allah be pleased with him) as a Mawquf tradition (a narration from a Companion, not directly from the Prophet). It is not مرفوع (Marfu', directly attributed to the Prophet, peace be upon him).

Even if the narration were authentic, it does not indicate that the familiar night and day were created before the heavens and the earth. The angels' glorification of Allah day and night does not necessitate the existence of day and night as we know them for them. Rather, it means their continuous glorification at all times.

Ibn Taymiyyah clarified that the night and day resulting from the sun were not created before the heavens and the earth; rather, they are subsequent to them. The sun and moon were created with the heavens and the earth, and they are in the celestial spheres (the heavens).