Genesis 30:16

And Jakob came from the field at evening. And Leah heard the voice of the braying of the ass, and knew that Jakob had come, and Leah went forth to meet him, and said, Thou wilt enter with me, because hiring I have hired thee with my son's mandrakes from Rahel my sister.

אלי תבא כי שכור שכרתיך, you will not commit any unfair act by canceling the date you had for tonight with my sister. My invitation to you has her full approval. This story, which appears on the surface as below the dignity of all the parties involved as it is described as if two women were engaged in horse-trading, Yaakov being the “horse,” must be viewed as proof that what was at stake was not Yaakov being used as a sex object but as illustrating how important having children by this man was to these sisters. The attitude towards intimacy with one’s husband displayed by both Leah and Rachel was akin to that of Adam and Chavah before the sin, when neither of them had any thoughts of fulfilling biological urges. Their entire purpose in mating had been to fulfill G’d’s commandment to become fruitful. Similarly, the motivation of the matriarchs was so highly esteemed by G’d. The use of the mandrakes to further their respective desires to conceive and produce children must be seen as something augmenting their prayers, so that on account of that G’d did listen to their prayers. It is proper for the righteous to exhaust all natural means to attain their laudable objectives before relying on miracle, i.e. prayer to attain them. This is also the deeper meaning of Yevamot 54 that G’d looks forward with great interest to the prayers of the righteous. The Talmud means that sometimes withholding something from them until they have exhausted their own efforts at securing their objectives by their own efforts will eventually result in their asking G’d to go out of His way to grant their requests.

וישכב עמה בלילה הוא, willingly, not reluctantly. He appreciated her urgent desire to have more children fathered by him.

ויבא יעקב, the reason why this whole paragraph has been preserved in the Torah for all times is to demonstrate that what motivated our matriarchs in their relations with their husbands was exclusively their task to produce as many children for them as possible. They were not concerned with indulging their libido. When Rachel, during those years, made a point of sleeping with Yaakov at every opportunity, it was because she hoped that on one of those occasions her prayers would be answered and that she would conceive. We find that in verse 22 this did indeed happen. It stands to reason then that when Leah requested that Yaakov sleep with her on a certain occasion, she too prayed that she would conceive as an answer to her prayers. She had resumed praying for additional children as soon as she had noticed that she no longer seemed to become pregnant easily. G’d did indeed listen to her prayer as we know from verse 17. As to Leah going out towards Yaakov while the latter was on his way home from work, she did this fully in accordance with accepted moral ethical rules, seeing that Yaakov had been unaware of the bargain Leah had made with Rachel. Had she not headed him off, Yaakov would have proceeded to Rachel’s tent, as was his custom. It would have been most inappropriate for Leah to ask Yaakov to leave Rachel’s tent after he had already arrived there.

אלי תבא, to my tent, seeing that each of the matriarchs had her own tent.

בלילה הוא the noun has the definitive article, i.e. the patach under the letter ב in the word בלילה, whereas the adjective, the word הוא, does not have the prefix ה which would signal such a definitive article, i.e. referring to a specific night we already know about. There are many such constructions in the Torah, one of the best known ones being in Numbers 28,4 את הכבש אחד, where we would have expected the word האחד instead of merely אחד. Samuel II 6,3 is another such example where we would have expected the word החדשה instead of חדשה.