"In den Abend" or "im Abend" - the case of Abend followed by "in"

Question

I wanted to say:

In the evening I go home.

I originally thought "in" would be followed by the accusative, which I found on the internet was correct:

In den Abend gehe ich nach Hause.

But when I was looking at the following article:

as a temporal preposition, “in” can be translated as “in,” where a period of time is implicit. Take note that, as a temporal preposition, “in” is dative:

I then realised it must be:

Im abend gehe ich nach Hause.

However, I found on some pages that "In den Abend" is correct and on others "im Abend" is correct instead.

Which is correct?

Answer 1

The preposition in is used with seconds, minutes, hours, weeks, months, and years.

… in der ersten Minute …

… in der zweiten Stunde …

… in der dritten Februarwoche …

… im dritten Monat schwanger …

… im Jahr 1989 …

With other spots in time, you have to use the preposition an:

… am Abend …

… am 14. Februar …

… an Werktagen …

… an den Wochenenden …

Unfortunately, there's an exception. Some directions need in, too:

… bis in den Morgen …

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But your question was about dative vs. accusative case. That depends on whether you talk about a place or direction in time:

Ihr Termin liegt in der dritten Februarwoche.

The verb liegen requires a place.

Wir verschieben Ihren Termin in die dritte Februarwoche.

In contrary, the verb verschieben requires a direction.

You example is a bit tricky because the verb gehen can take both a place or a direction. An example with real places:

Am Abend gehe ich am Strand.

Am Abend gehe ich an den Strand.

In time, prefixed verbs as losgehen and weitergehen are preferred:

Die Feier geht am Abend los.

Die Feier geht bis in den Morgen weiter.

Answer 2

None of those are correct. Here are two possibilities

Am Abend gehe ich nach Hause
Abends gehe ich nach Hause

You could use "in den Abend" in a a context like this

Ich habe bis in den Abend hinein gearbeitet (I worked into the evening)