Greeting one another after being separated
The Prophet (sal Allahu alaihi wa sallam) said, “When one of you meets a brother (in Faith) he should greet him. Then if a tree or a wall or a stone intervenes between them and then he meets him again, he should greet him.”
[Sunan Abu Dawud]
We benefit from this Hadith that if a tree or a wall or a stone or something similar intervenes between two people and then they meet again, they should greet one another.
And Allah knows best!