Article 2243 of Mexico’s Federal Civil Code allows a party to promise to sign a contract in the future. Under Article 2246, the promise “debe constar por escrito” (must be in writing). It must also contain the essential elements of the final contract and be limited to a set time. If the promisor then refuses to sign, “en su rebeldía los firmará el juez” (the judge will sign in his place), under Article 2247.
A spoken promise with no date fails at least two of these conditions.
Dios mediante, “God willing.” Si Dios quiere, “if God wants.” In 2020, the political scientist D. E. Vilchis Carrillo published a study in the journal Política y Cultura titled “Participaré… si Dios quiere” (I will take part… if God wants). He describes the two phrases as popular expressions of Mexican Catholic culture, which “se usaban cada vez que se expresaba algún deseo futuro” (were used whenever a wish for the future was expressed).
Yo te aviso, “I’ll let you know.” Ahorita, a la vuelta, “in a little while, on my way back,” said to a street vendor. Ahí para la otra, “next time, then.” Déjame pensarlo, “let me think about it.” En un ratito, “in a little while.” In 2017, Matador Network in Spanish listed these among nine expressions Mexicans use to avoid saying no.
Ahora means “now.” Mexicans add the diminutive and say ahorita, “little now.” The word can mean right now, in a moment, or later. A study in the linguistics journal of El Colegio de México found that in Mexico City ahorita is used in contexts where it cannot be read as an exact moment.
For real urgency, speakers double the diminutive: ahoritita.
Quedar bien, “to come out well,” means to leave a good impression and keep things pleasant. Mexican Spanish has many phrases that serve it.
Sí, cómo no: “Yes, of course.”
Primero Dios: “God first,” meaning “God willing.”
Ahí lo vemos: “We will see about it.”
Ahí nos vemos: “See you there.”
Each can be a firm promise. Each can also be a kind way to leave a request open.