Delaying a task is a common human flaw, but procrastination becomes deeply harmful when it affects another person's well-being or one's own spiritual growth. The wisdom here condemns the act of withholding immediate help or payment when the ability to act is readily available.
The primary approach among commentators is that this situation involves someone asking for a favor, such as a poor individual seeking charity [רש״י] or a friend asking to borrow an item [ביאור שטיינזלץ, מצודת דוד]. Beyond acts of kindness, it equally applies to someone who is legally owed money, like a hired laborer waiting to receive their wages [רש״י, אלשיך, ביאור שטיינזלץ]. Sending a person away empty-handed and telling them to return the next day can stem from various motivations. Sometimes it is born of simple laziness or an unwillingness to help, while other times it is a deliberate tactic meant to make the recipient feel the burden of the favor so they will appreciate it more [ביאור שטיינזלץ]. Regardless of the motive, treating a person this way is a degrading and humiliating experience for the one making the request [אבן עזרא].
This behavior is strictly forbidden when the requested money or object is already in your possession and can be given without delay [מצודת דוד, רש״י]. There are practical reasons why one must not postpone doing good. The ability to help might be lost by the next day, or the requester's need might be so critically urgent today that receiving help tomorrow would be entirely useless [עמנואל הרומי, מלבי״ם]. Furthermore, if a person is warned not to withhold a voluntary favor from someone they owe nothing to, it is certainly forbidden to delay paying a debt to a person who is already entitled to that money [אלשיך].
Alongside these practical interpersonal lessons, there is a profound spiritual dimension regarding procrastination in serving God and studying His wisdom. In this spiritual context, the companion being delayed is understood as a reference to God Himself. One must not postpone studying His teachings until tomorrow, because whenever such study is neglected, the Divine Presence departs. The ability to engage with this wisdom is never out of reach; it is always present and accessible within a person's mouth and heart [ראשון לציון].
Another perspective views this interaction internally, linking the concept of a companion to the emergence of a new thought or idea. When an internal desire to learn and seek wisdom awakens, a person must seize the moment while their mind is eager and ready. Pushing off that intellectual inspiration until tomorrow risks losing the opportunity entirely, as the desire may vanish forever [עמנואל הרומי]. Spiritual growth should never be postponed with the excuse of waiting for free time. Instead, a person must act immediately, especially during the prime years of their youth [מלבי״ם].