What is the ruling on a person who catches up with one takbeer of the imaam in the janaazah (funeral) prayer, but he has missed three takbeers? What should he do?

Praise
be to Allaah.

He should complete the janaazah prayer and recite the
three takbeers to make up what he has missed before the coffin is taken
away, then he should say the salaam. The part of the prayer where he
caught up with the imaam is considered to be the first part of his prayer,
and it is sufficient for him to say the minimum of what is required
after the second and third takbeers. After the second takbeer he may
say, “Allaahumma salli ‘ala Muhammad (O Allaah, send blessings upon
Muhammad)” and after the third takbeer he should say, “Allaahumma ighfir
lahu (O Allaah, have mercy on him).” And he should say salaam after
the fourth takbeer. 

And Allaah is the Source of strength. May Allaah bless
our Prophet Muhammad and his family and companions, and grant them peace.