Broken shofar blasts shatter din; the whole tekiah unifies

איתא בזוה"ק יודעי תרועה דמתברין האי תרועה כי תרועה ושברים הם קולות נפסקים ונחלקים.

It is taught in the Zohar: "those who know teruah" — that they break apart this teruah; for the teruah and the shevarim are broken and divided sounds.

The shofar's teruah and shevarim are fragmented, staccato blasts — sounds that are deliberately broken into pieces.

שמדת הדין צריכין לשבר ולחלקה לחלקים.

For the midas hadin (attribute of strict justice) must be broken and divided into parts.

The broken sounds correspond to shattering the force of strict judgment, dividing it so that it cannot stand whole against us.

ואז נעשה מגבורה ג' פעמים חסד.

And then, from gevurah (severity), it becomes three times chesed (kindness).

When the single force of din is broken into parts, its severity is transformed and sweetened into kindness — multiplied as chesed.

וכ"כ בשמעון ולוי אחלקם ביעקב ואפיצם כו'.

And so it is written regarding Shimon and Levi: "I will divide them in Yaakov and scatter them…"

Shimon and Levi embodied harsh gevurah; Yaakov "divided and scattered" them precisely to break and temper that severity, the same principle as the broken shofar blasts.

אבל תקיעה היא קול אחד שלם.

But the tekiah is a single, whole sound.

In contrast to the broken teruah and shevarim, the tekiah is one unbroken, complete blast.

והיא מדת אברהם דכתיב אחד הי' אברהם.

And it is the middah of Avraham, as it is written "Avraham was one."

The whole, unified tekiah corresponds to Avraham, who embodied oneness and the unifying attribute of chesed.

וכ' ובהקהיל כו' הקהל תתקעו ולא תריעו כי התאספות והתחברות הוא במדת התקיעה:

And it is written "And when you gather… the assembly, you shall blow a tekiah and not a teruah," for ingathering and unification belong to the attribute of the tekiah.

To assemble and unite the people, the Torah prescribes the unbroken tekiah, not the broken teruah — because gathering together is the work of unity, the quality of the whole sound and of Avraham's oneness.

Summary: The broken sounds of the shofar — teruah and shevarim — represent the shattering of midas hadin, dividing strict judgment so that its severity (gevurah) is transformed into abundant chesed, just as Yaakov "divided and scattered" the harshness of Shimon and Levi. The unbroken tekiah, by contrast, is the whole sound of unity, the middah of Avraham who "was one"; therefore the Torah commands the tekiah for ingathering, since assembly and unification belong to the unbroken blast.