Luqman: (15) And if they strive to make you join with Me...
This means that serving them (parents) is obligatory and obeying them is necessary, unless it involves abandoning obedience to God.
If (their command) leads to that (abandoning God's obedience), then do not obey them. We have already mentioned the exegesis of this verse in Surat Al-'Ankabut (The Spider).
Here, He said: {And follow the path of him who turns to Me}. This means: accompany them (parents) with your body, for their right is over your physical self. And follow the path of the Prophet (peace be upon him) with your intellect, for he is the nurturer of your intellect, just as the father is the nurturer of your body.
{O my son, indeed, if it should be [as small as] the weight of a mustard seed and hidden within a rock or in the heavens or in the earth, Allah will bring it forth. Indeed, Allah is Subtle, Acquainted [with all things].} (31:16)