Musar על בבא מציעא 132:26

Jacob prefaced his vow with the words: אם יהיה אלוקים עמדי, If the Lord will be with me, etc." He concluded it by saying that if his request would be granted: והיה ה' לי לאלוקים, "then the Lord will be my G–d." How could Jacob have dared to use the word אם, "if," which suggests that he made his loyalty to G–d dependent on G–d fulfilling his requests? We have a halachic ruling in Baba Metzia 66 that if someone purchases something by prefacing his remarks with the conditional word אם, such a purchase is invalid, seeing he had not truly committed himself. Even though the Maharam rules that in matters of vows and oaths conditional vows are legally binding, why did Jacob use an expression involving him in possibly legally binding vows? ...