As with the anointing oil, only a certain mixture of four ingredients was acceptable as incense for burning on the incense altar. Similarly not just any prayer is acceptable to God; only prayers offered as He has instructed will be acceptable (cf. 1 John 5:14).
"Stacteis a fragrant resin obtained from some species of cistus, or rockrose.' Onychais the horny plate that covers a species of mussel found in the lakes of India which, when burned, emits a musky odor. Galbanumis a pleasantly aromatic gum resin derived from certain umbelliferous plants. Frankincense(from the Old French for pure incense'), as used by the Jews, Greeks, and Romans, was a gum resin now called olibanumwhich was derived from certain trees of the genus boswelliafound growing on the limestone of South Arabia and Somaliland. Thus, three of the four ingredients in the incense burned on the golden altar were gum resins. Gum resins are mixtures of gum and resin obtained from plants or trees by incision. Resins burn readily because they contain volatile oils."496
