When someone dies!
When someone dies, the greatest favor that you can do for them is to pray for them, especially if they were in low mental and energetic states when they made their transition.
Your lightened energy directed towards them can help them make the tansition from the heavier Earth vibration to raising to a higher one to allow them to actually "pass over" to a higher dimension between their lifetimes. Yogi Bhajan let us know that a Soul normally stays within the Earth's vibration for 17 days after it leaves its body in order to clear up and learn what they need to, as well as get a boost for the next stage.
So, when a person does leave their body, we customarily chant the mantra Akal at least three times for them. This is quite powerful in a large group. Or you can chant it on your own, and chant it as long and as much as you want.
"Akal" means Undying. And the vibration of it helps that personna become aware of the Light that is waiting there for It. Of course, the idea is for the person to merge into that Light!
This is also a wonderful thing to do if you feel that a bodiless spirit, also called a ghost is in your presence or if they seem to hang out in a certain location. Don't be afraid or shy. Just chant this amazing mantra for them so that they can move on if they are inclined to.
HOW TO CHANT AKAL.
The sound of Akal is "uh-call." When you chant it, you first take a full, deep breath. Then you chant the mantra for the full, extended length of that deep breath. The first syllable "uh" is short, and the second syllable flows on the whole remaining length of your breath. It is chanted in a comfortable monotone. Do this at least 3 times. But you can do it as long as you want.
If you get into chanting Akal as a mediation, you may find that you actually can sense that person and feel when they head for the Light, and perhaps even glimpse that Light yourself. But if you don't get that feedback, don't worry. You have done a great and wonderful thing for that person!