1,290. After the Burial
199:9 If the deceased's son is present in the cemetery, then after the burial, if there is still time remaining in the day, we move at least four cubits (about six feet) from the graves and recite Psalm 49. On a day on which we don't recite Tachanun, we recite Psalm 16 instead. The son of the deceased recites a special form of kaddish that includes the phrase "d'Hu asid l'ischad'ta," that G-d will create the world anew. The rest of the people recite along with him until the word "vayikarei." In some places they have the practice to recite the kaddish before the burial, after Tzidduk HaDin. In other places Tzidduk HaDin isn't said until after the burial.
199:10 The practice when leaving the cemetery is to pluck some grass and to throw it over one's shoulder, saying Psalms 103:14, "He remembers that we are dust." This is also a sign of the resurrection of the dead, who will be restored from their dirt, as suggested by Psalms 72:16, "May they flourish in the city like the grass of the earth." This may also be done on chol hamoed.
After this, those departing the cemetery wash their hands. This is a sign that this form of ritual impurity is only cleansed through three things: water, the ashes of the red heifer and hyssop. The hands should not be washed by placing them in running water; one should pour from a vessel. The vessel should not be taken from the hand of one who just used it. Rather, one person places it down and the next picks it up. One does not dry his hands.
Some authorities say that a person should sit down seven times because of harmful forces that accompany him; every time one sits down, the forces depart from him. In some places, they have the practice to sit down three times after washing. Each time one sits, he recites "VaYehi Noam." When the deceased is buried on yom tov, those departing the cemetery can sit three times as they do on weekdays.
The practice is to be stringent that we wash our hands and sit before entering a building. The practices accepted by our ancestors are like laws to us.