Heating aliphatic carboxylic acids with glycerol (and optionally a catalytic amount of a strong mineral acid) will esterify the components to form various triglyceride esters. The procedure is called
Fischer esterification. It will not happen at room temperature (>100°C is suitable) or in aqueous solution.
Neither "oil" or "butter" could be classified as "aliphatic carboxylic acids" though. Stearic acid could, however, and is the main constituent of top-grade old-style candles.
Here is a PPT presentation dealing with the esterification of Glycerol with Stearic Acid, forming Tristearin (a triglyceride ester):
http://www.chem.uic.edu/wardrop/teaching/chem234/files/WARDROP-234-17.ppt