Gen 49:4

“He said "couch" and "bed," that is, the holy flesh of Christ, on which the saints are saved while enjoying their rest as on a holy divan. This is the flesh that those outlaws took possession of and then outraged by offering him [Christ] vinegar, by hitting his head with a reed, by flogging him on the back, by spitting on his face, by skinning his cheeks with slaps and by piercing his hands with nails. All these things the impious and unbelieving people did in accordance with the high priests, the scribes and the leaders of the people. That is why the blessed prophet neither has remained silent about their deeds nor wants to be involved in their wickedness and evil decisions. On the contrary, he keeps himself away from their intrigues where such criminal plots are conceived.”

“Just as the justice of Jacob cursed his firstborn because of his evil deed and this curse of Reuben was blotted out by Moses who was the descendant of Jacob, so too was death decreed by God against Adam when he transgressed the commandment. But the Son of God came and, with the promise of the resurrection that he promised, brought to nought the judgment that accompanied Adam out of paradise.”

“Doesn't this seem to be a reproach rather than a blessing? Thus it really is more a prophecy than a blessing. For a prophecy is an announcement of events to come, whereas a blessing is the longed for bestowal of sanctification and of graces.The Jews suppose that the old man is saying these things to his son Reuben on this account, because the latter lay with Bilhah, his father's concubine, and polluted his father's bed. But they are easily refuted; this had already taken place. Now Jacob is promising that he will speak of events to come in the last days, not what took place before. Therefore the meaning is consistent and in accord with the thought of the patriarch himself: he sees the future passion of the Lord under persecution from the Jews and execrates the boundless audacity of that firstborn people.… For Israel itself was called the firstborn and said to be stiff-necked, and of it Moses said, "You are a stiff-necked people."”

“See how through the insight granted him by the Spirit Jacob anticipates the legislation of Moses against allowing father and son to have relations with the same woman. Ahead of time he forbids this in censuring his son thus, "You stained the couch" by entering your father's bed. You committed an unlawful act, he says. Hence "you ran riot like water, but you shall not break out again."”

“פחז כמים The impetuosity and the precipitance with which you so hastily showed your wrath, just like water that rushes headlong in its course — therefore אל תותר THOU SHALT NOT BE SUPERIOR— you will not receive all these many prerogatives that were proper to you. And what was this impetuosity which you displayed? כי עלית משכבי אביך, אז חללת BECAUSE THOU WENTEST UP TO THY FATHER S PLACE OF REPOSE; THEN PROFANEDST THOU Him Who hovered over my couch — the Name of the Shechina that used to abide above my couch (Shabbat 55b and Rashi there). פַּחַז is a noun (a segolate noun like נַחַל) and has its accent therefore on the first syllable, and the entire word (both syllables) is punctuated with Patach, for were it the past tense of a verb, half of it (the first syllable) would have been punctuated with Kametz and the other half with Patach, and its accent would have been on the last syllable. יצועי denotes a couch, because it is spread (root יצע) with mattresses and sheets; it occurs in this sense frequently in Scripture: (Psalms 132:3) “Nor go up into the bed that is spread for me (ערש יצועי)” ; (Psalms 63:7) “When I remember thee upon my (יצועי) couch”.”

“UNSTABLE (‘PACHAZ’) AS WATER, YOU HAVE NOT THE EXCELLENCY. Pachaz is a noun, derived from the expression, Vain and reckless (‘upachazim’) fellows, meaning “hasty and impulsive people.” Our Rabbis have made steady use of this word: “I was looking at my image in the water and my evil inclination rose (pachaz) within me,” that is “my evil inclination leaped upon me” They said further: “It is their recklessness (apichzeihu) which they are revealing,” meaning their impulsiveness. “A reckless (p’chizah) people, who spoke before listening, you still retain your recklessness (‘b’pachzuteich’),” meaning “hasty and impulsive.” It is possible that this word pachaz is a permutation of the word chipazon (hurry). and kesev, both of which mean “lamb,” and other similar words. Jacob was thus saying: “Since you burst forth as water, you shall no longer excel for thou wentest up to thy father’s place of repose in thy haste and impulsiveness. Then didst thou profane them, (places of repose), which is in the plural form. Hence Ramban writes otham (them). when your recklessness ascended my couch like the rising and gushing water.” This is similar to the Scriptural description of water: Now, therefore, behold, the Lord bringeth up upon them the waters of the river, mighty and many, even the king of Assyria and all his glory; and he shall come up over all his channels, and go over all his banks; and he shall sweep through Judah, overflowing as he passeth through. Our Rabbis have said: “Then didst thou profane He Who hovered over my couch, meaning the Shechinah” that used to abide above my [Jacob’s] couch. Yet the verse says, Forasmuch as he [Reuben] defiled his father’s couch,. Ramban proceeds to answer that Scripture modifies the expression out of respect for the Divine Presence. thus clearly stating that it was the couch which was defiled! But perhaps [out of respect for the Divine Presence, Scripture] modifies the expression there. But if [we accept the explanation that Scripture modifies the expression], it is possible that the word alah (going up) refers to [Jacob, thus saying, “then didst thou profane my couch upon which I used to go up],” just as in the verse, Nor go up into the bed that is spread for me. Thus Jacob’s intent is to say: “Then thou didst defile me;” He spoke in the third person, “he” went up. only as a matter of respect. Similarly, the verse, Forasmuch as he defiled his father’s couch, is a Scriptural modification, meaning “forasmuch as he [Reuben] defiled the one who goes up upon his father’s couch.” From the literal meaning of this verse it would appear as I have explained it in Seder Vayishlach, i.e., that it was Reuben’s intention to disqualify Bilhah from his father so that she should no longer give birth to children, thus lessening his share as the firstborn. It was for this reason that Jacob said to him that it was reckless and impulsive to think that he would gain thereby, whereas he had no profit from it but only loss.”

“Carnal concupiscence took from us our noble generation, by which we would all be born innocent and heirs of paradise, and it makes us be born in death and guilt and the loss of the birthright. This was prefigured in Reuben, who lost the right of the firstborn, because he went up to his father's bed and defiled his couch; and Joseph, on account of his chastity, was made prince over his brothers.”