(13) You must be wholehearted with Adonai your God.
(1) תמים תהיה עם ה' אלהיך You shall be wholehearted with Adonai your God — walk with God whole-heartedly, put your hope in God and do not attempt to investigate the future, but whatever it may be that comes upon you accept it whole-heartedly.
(1) תמים תהיה, whole-hearted to the extent that you will not even try and gain information about future events except through an authentic prophet.
"You should know that the precepts of the heart imply a complete harmony between our inner and outward actions [...] till the heart and tongue and other limbs will be at one with each other, each one justifying and bearing witness in favor of the other, neither contradicting nor belying each other." --Bahya Ibn Paquda, Hovot Ha-levavot (Duties of the Heart)
Rabbi Harold Kushner
(How Good Do We Have to Be? p. 180)
That, I believe, was what God asked of Abraham. Not "Be perfect," not "Don’t ever make a mistake," but "Be whole." To be whole before God means to stand before God with all our faults as well as our virtues and to hear the message of our acceptability.… Know what is good and what is evil, and when you do wrong, realize that that was not the essential you. It was because the challenge of being human is so great that no one gets it right every time. God asks no more of us than that.
When we show up wholeheartedly, it means we are able to appear as we truly are, not attempting to hide ourselves, but accepting ourselves. These verses and commentary speak of showing up wholehearted before God. Even when our own theology doesn't bear that idea out, we can consider showing up wholeheartedly in our actions with others as well as with ourselves. That then is the task of the month of Elul: preparing ourselves to appear before God tamim, wholehearted, when we arrive at the high holidays. How fitting that we receive that reminder in the month of Elul, through our Torah readings, as a reminder to continue to work on making our whole selves become more intact.