Garuḍa Purāṇa 17
There is no salvation if one does not have a son. Even if salvation is not possible, one needs to have a son to avoid going to hell. Cremation rites can be performed only by a son. Immediately after death, the place is to be cleansed, smeared with gingelly seeds and darbha grass. If one happens to know that someone is going to die shortly, he/she should be placed on the bed of darbha grass. If he dies on the bed of darbha grass, a portion of his sins will be eliminated. Before performing śrāddha rites, the place where the ritual is going to be performed, should be cleansed. Lord says that gingelly seeds originate from His sweat and hence considered sacred. There is a reference to a mystic diagram. The epic says that no śrāddha rite should be performed without drawing this mystic diagram. The importance of gingelly seeds is repeatedly emphasized throughout Garuḍa Purāṇa. Similarly, the Lord says that darbha grass originates from His hair. It is also said that performing these rites, one should wear sacred thread, without which, rituals will not confer any benefits. When the sacred thread is on the left shoulder, Brahmā and other Gods are present in the holy thread. If the thread is worn on the left shoulder, pitṛ-s are worshipped. Brahmā, Viṣṇu and Śiva are present in the bottom, middle and the tip of darbha grass.
Knower of Vedas, mantras, darbha grass, fire and basil plant never become impure under any circumstances, and they can be repeatedly used. However, there are some exceptions. Knower of Vedas becomes impure after taking food in preta rituals. Darbha grass becomes impure if used in piṇḍa offerings. Funeral fire is not holy. Mantras are of no use, if recited by those who have no faith in sacred rites. Basil, knowers of Vedas, holy cows, Lord Viṣṇu and ekādaśī day (eleventh day of lunar fortnight when one fasts for the whole day) are the five sacred boats that make a person become eligible for liberation (however, this is subject to one’s karma. Karma is the ultimate factor in deciding transmigration or liberation. (There are enough articles on karma in this site and you can use the search in manbluder at the top of this site.) River Ganges is also mentioned along with these five that is capable of offering liberation. Cooking salt (crystals) is said to have originated from the body of Viṣṇu and pitṛ-s are very fond of salts and is said to be the doorway to the heaven. Hence vessels with salts should be given as gifts.