וַיְהִי֮ בַּלַּ֣יְלָה הַהוּא֒ וַיֹּ֧אמֶר ל֣וֹ יְהוָ֗ה קַ֤ח אֶת־פַּר־הַשּׁוֹר֙ אֲשֶׁ֣ר לְאָבִ֔יךָ וּפַ֥ר הַשֵּׁנִ֖י שֶׁ֣בַע שָׁנִ֑ים וְהָרַסְתָּ֗ אֶת־מִזְבַּ֤ח הַבַּ֙עַל֙ אֲשֶׁ֣ר לְאָבִ֔יךָ וְאֶת־הָאֲשֵׁרָ֥ה אֲשֶׁר־עָלָ֖יו תִּכְרֹֽת׃
And it came to pass the same night, that the LORD said unto him: ‘Take thy father’s bullock, and the second bullock of seven years old, and throw down the altar of Baal that thy father hath, and cut down the Asherah that is by it;
Shenei Luchot HaBerit
A person must purify his heart before he commences to pray (Shemot Rabbah quoted by Menorat HaMa'or page 39). We also find that Job referred to the fact that "there is no injustice on my palm, my prayer was pure." Rabbi Joshua the priest, son of Nechemyah queries how a prayer could be עכורה, murky, dirty. He concludes that the statement about Job's prayer not having been offered with hands soiled with violence does not refer to hands that are physically dirty but to the stains caused by sin. A person who has not first removed sin from himself calling upon G–d is not likely to be answered. Gideon, who was descended from the tribe Manasseh, excelled in those two attributes. He demonstrated this even before he destroyed the altar dedicated to the idol Baal and by subsequently building an altar for G–d and sacrificing on it (Judges 6:25-28).